Dermot O'Leary claims Louis Walsh is the dirtiest 'X Factor' judge.
The 41-year-old presenter - who has hosted the ITV singing competition since 2007- has revealed that Louis, 62, is the most ruthless member of the judging panel ahead of his co-stars former Spice Girl Mel B, Cheryl Fernandez-Versini and even the show's boss Simon Cowell.
According to Dermot, the entertainment manager often resorts to unsavoury tactics in a bid to win the show.
He told The Sun newspaper: "I love it when the panel is fun and when they are a bit spikey with each other, so long as they don't resort to the proper dirty stuff like Louis does.
"If I was a contestant, Louis would be the judge I'd want because when we go to the studios he is the dirtiest judge we have."
However, Dermot insists Louis' "unorthodox" antics make him the most "valuable" judge as his "unconventional" mentoring methods keep the show interesting.
He explained: "He's unorthodox and unconventional but I couldn't make the show without Louis.
"I adore him."In many ways he's the most valuable person on the panel. I can always rely on him to give me a tiny bit of insanity.
"He laughs when everyone else cries and cries when they laugh. He walks to the beat of his own drum. He's an extraordinary man."

'EastEnders' bosses will reveal the identity of Lucy Beale's killer during a live episode to mark the soap's 30th anniversary.
The BBC One show first aired on 19 February, 1985 and to celebrate 30 years on air, 'EastEnders' has announced there will be a week of live episodes, starting from 16 February, 2015. The excitement doesn't stop there though, as the live episodes will conclude with the revelation of who murdered Lucy Beale (played by Hetti Bywater), who was dramatically killed in April.
Charlotte Moore, Controller of BBC One, said: "BBC One will bring the nation together to celebrate 30 years of EastEnders by going live across the anniversary week. Next February will mark a massive event on the channel by creating the ultimate 'doof doof' and finally reveal who killed Lucy Beale."
Ben Stephenson, Controller of Drama Commissioning, also added: "'Live week' allows us to keep loads of secrets from the cast, crew and the audience until the very last minute.
"With shocking reveals and un-guessable twists it's going to be a week that will change Albert Square forever."
This isn't the first time 'EastEnders' has attempted to 'go live' for the show. In 2010 the cast celebrated the soap's 25th anniversary with a live episode and during the 2012 London Olympics the cast and crew shot several live segments.

Josie Cunningham could be set to star in 'I'm a Celebrity... Get Me Out of Here!' - just weeks after giving birth.
The controversial glamour girl is reportedly in talks with ITV to go into the jungle, despite the fact she only gave birth to her daughter on Monday (29.09.14).
Josie found herself hitting the headlines back in March 2013, after it was revealed that she had used the NHS to fund her breast enlargement operation. She then angered the nation after she admitted she had considered having an abortion because it would improve her chances of appearing on the Channel 5 reality show, 'Big Brother'. Although she changed her mind, the 24-year-old mother of three continued to infuriate people as she confessed to smoking and drinking throughout her pregnancy.
However, a source has revealed the Leeds-born brunette hopes an appearance on 'I'm A Celeb...' - which is scheduled to start in November - could show the British public the 'real' Josie.
Talking to The Sun newspaper, the insider said: "She hopes that by doing Bushtucker Trials - which she expects - the nation will see a different side to her and like her. It's hard. She wants to be with her kids and keep a low-profile. But she could earn more than £100,000."

'EastEnders' star Danny Dyer cried tears of pride as he watched his
daughter pose for photographers at the screening of her new film.
The actor and his long-term partner Joanne Mas joined their actress daughter Dani at the premiere of crime drama 'We Still Kill The Old Way' at the Ham Yard Hotel in London on Monday night (29.09.14) and as Danny let the 18 year old take her moment in the spotlight he couldn't contain his emotions.
An onlooker said: "Dani was really nervous before arriving at the event, but her dad walked her through everything and showed her the ropes. "He couldn't hide his excitement at seeing his daughter follow in his footsteps. At one point he and Joanne were cheering and clapping but then he broke down into tears and the film's producer Jonathan Sothcott had to run and get him some tissues."
In the hard-hitting movie, Dani's alter-ego gets involved with a gang of hoodies which results in her being raped by the character played by actor Danny-Boy Hatchard - who portrays Danny's on-screen son Lee Carter in 'EastEnders'. An event that brings a firm of old-time gangsters out retirement to clean up the streets of their old patch.
Danny - who plays Queen Vic landlord Mick Carter in the BBC One soap - admits it was hard to watch his daughter in such a traumatic scene but is very proud of her performance.
Danny, 37, said: "She was absolutely amazing, I'm so proud of her. She's a chip off the old block, but she's just done her first lead role and she didn't ask her dad for one bit of advice through the whole thing."
Referring to the rape scene, he said: "Watching that ain't easy, let me tell you. I wanted to put Danny-Boy's throat into the wall when I saw that, but he's a good kid and a bloody good actor so I eased up and I'll have a beer with him. They've all done great."
Producer Sothcott - Danny's most prolific on-screen collaborator and the man who gave his daughter her first role, opposite her dad in movie 'Vendetta' - teased the Walfrord resident. claiming his time as a big screen hardman is up.
He joked: "We don't need you any more. Danny. You're finished! We've got the next generation now."
Other celebrities at the screening included 'Game of Thrones' star Anouska Mond - who stars in the movie - former 'Celebrity Big Brother' housemate Casey Batchelor, Lucy Pinder and Bruce Payne.

Simon Cowell has cut scenes of 'X Factor' hopefuls swimming with dolphins from this weekend's 'Xtra Factor'.
A preview clip of the Judges' House round showed Mel B's acts from the boys category in a pool with the aquatic mammals and singer Paul Akister, 25, was also seen sharing a kiss with one of the dolphins.
The aired footage - due to be screened on spin-off show 'The Xtra Factor' -sparked anger among viewers of the ITV show and an online petition gained almost 8,000 supporters demanding it be removed.
But once animal lover Simon found out about the trip to see the captive creatures he made the decision to axe the scenes from the final show.
Writing on his Twitter account, he revealed: "Reading your tweets. I had no idea Xtra Factor producers filmed with dolphins. This will NOT be showed on Saturday.
"I think you all know my view on cruelty to animals so thank you all for your concern. (sic)"
The Judges' House stage will see the four mentors, Simon, Mel B, Cheryl Fernandez-Versini and Louis Walsh, pick their final three acts to go on to the live shows.

Diddy believes Jennifer Lopez's bum is a "work of art".
The 44-year-old record producer - who dated J-Lo, 44, for two years in 1999 - gushed over the 'Get Right' singer and insists he is "lucky" to count her amongst his exes.
He told Access Hollywood Live: "Oh my God. I'm so lucky to have that great woman in my history, she is one of the greatest I've ever seen.
"I mean, it's great. It's a work of art. It's something that will go down in history, for real it will. But also her talent, her drive, her determination, she will never give up. She's a great friend of mine, always will be my friend, and I mean that thing is just incredible, man."
The 'I Need A Girl' rapper also slammed Kim Kardashian's famous backside and added that it is "no way" comparable to Jennifer's curvaceous posterior, although he hopes his decision won't upset Kim's husband, fellow rapper Kanye West.
When asked by host Billy Bush if the reality TV star's bottom rivals that of the 'Booty' hitmaker, Diddy said: "No way! "No way. No disrespect to Kanye and Kim but that thing right there, that thing right there is something special."

Jennifer Lopez was "super scared" during her recent drink-drive crash.
The 'Love Don't Cost A Thing' hitmaker - who was rear-ended by an intoxicated pick-up driver as she test drove her new car with her close friend Leah Remini down the Pacific Coat Highway in California last week - has relived the terrifying moment they were struck.
The 45-year-old singer's first thought during the smash was to "fight" for her kids, six-year-old twins Max and Emme, who were sitting on the back seat along with Leah's 10-year-old daughter, Sofia.
She told Extra: "Everybody's fine... just a little shook up. You know you get hit from behind like that, it felt l like a boulder fell on top of the car.
"I was super scared that something that happened to the kids... They say in situations like that you fight, flight, freeze. I didn't freeze, I fought, and I didn't leave, I fought... I was like, 'They were kids in the car! There were three kids in the car, what's wrong with you?'"
Jennifer first shared news of the crash on her Instagram account on Sunday (28.09.14).
She posted on the picture sharing site, along with a photo of herself and Leah, 44: "Sitting at a light, Riding high right before some drunk fool rear ended us in my new whip!!! Thank god everyone ok!!! #GRATEFUL #THANKYOUGOD.
"#DontdrinkandDrive!!!! #cursedthatfoolout #theBronxcameout #dontmesswithmycocnuts #mamabear #leahstayedcalm #thatwasweird (sic)".
After the pair called the police the authorities soon caught up with the drunk driver who was arrested on suspicion of DUI and hit and run a short distance from the crash.

Katy Perry has a "huge crush" on Harry Styles.
The 'Roar' hitmaker, who has been linked to DJ and music producer Diplo, 35, since April, recently enjoyed an intimate dinner with the One Direction hunk and the pair got along incredibly well.
A source said: "They like each other Katy and DJ Diplo are casually dating, but she's developed a huge crush on Harry, which she calls unexpected.
"He looks up to Katy and loves that she isn't your typical needy twenty-something."
Harry, 20, reached out to offer the 29-year-old beauty advice following her apparent falling out with his ex-girlfriend Taylor Swift, after the country star gave an interview and spoke about a "straight-up enemy" widely assumed to be Katy.
But the source also told the UK's LOOK magazine: "I think he's concerned Katy's playing him to get back at Taylor for supposedly bad-mouthing her.
"Harry reached out to Katy because if anyone knows how Taylor can be sometimes, it's him.
"Katy was touched and asked him to dinner. She's enjoying it, but there may be a little element of revenge behind it too."
Taylor is said to be "shocked" by the pair's closeness.
A source said: "She's shocked. Katy dating an ex? Yeah, that would hurt."

Brad Pitt's family make him feel like the "richest man alive".
The 50-year-old actor - who raises six kids, Maddox, 13, Pax, 10, Zahara, nine, Shiloh, eight, and six-year-old twins Knox and Vivienne, with wife Angelina Jolie - admits becoming a parent changed him completely and he loves helping his children grow up.
He told Psychologies magazine: "You learn to value the basic beauty of family, of watching your children grow and evolve. It's the most beautiful thing you can experience.
"Being a father has changed me on so many levels and made me more generous and alive."
He added: "I see my children as an essential part of my life, and it means so much to be able to educate them and help them make their way in the world as they grow up.
"I love being a father and all the responsibilities that entails. I feel like the richest man alive since I've become a father."
And the 'Fury' star admits he never stops worrying about his family and will always put them first.
He said: "I worry about them all the time. That's the emotional bond and responsibility that sweeps over you when you have a family to look after.
"I care about them more than I care about myself, which I think is the real definition of love. You see past yourself and become more generous and giving, and wanting only the best for your family."

Jeremy Renner says there are plans for him and Matt Damon to appear together in a Bourne film.
In September, a report suggested Damon and director Paul Greengrass would reunite for their third Bourne film together - but Renner, 43, admits a new flick could either see him team up with Damon's character or face off against him.
Asked whether another Bourne flick was still on the horizon, Renner told The Daily Beast: "Absolutely! They made it more exciting when Paul [Greengrass] and Matt [Damon] got back into the mix, and finally cracked a story idea for them to come back into it.
"I think they'll be separate movies, and then the idea is for us to either team up, or be adversaries."
The next film in the Bourne franchise is set to be released on July 16, 2016.
Meanwhile, it was recently reported that Damon, 43, is keen to secure the lead role in Legendary Pictures' 'The Great Wall', which will explore the mysterious origins of China's historic structure.
Deadline reports that Damon is being lined up to play the central character in the film, which Legendary's Thomas Tull - the producer - has been attempting to get made for several years.

Derek Hough felt "really protective" of Hayden Panettiere on the set of 'Nashville'.
The 25-year-old actress is expecting her first child with fiancé Wladimir Klitschko and the 'Dancing with the Stars' performer, who is set to guest-star in several upcoming episodes of the TV series, admits he was worried she might injure herself while working alongside him in Tennessee.
The 29-year-old star told UsMagazine.com: "I get really protective over pregnant women! I'm like walking around her with my arms out like, 'are you okay?! But she's still working, she's still rocking it!"
He added: "She looks great. She's amazing. I love her."
The heartthrob has very little acting experience, but received a warm welcome from the cast of the country music show.
He said: "Everyone was so kind, so sweet, and Hayden was incredible to work with. The whole cast and crew were so welcoming, they weren't like, 'Who's this guy?' They were really awesome."
Hayden is due to welcome a baby girl into the world later this year and previously claimed she was born to be a mother.
The blonde beauty said: "I've lived a very big life, and I don't feel my age, and I feel like I was born to be a mother.
"Sometimes people speak about [having kids] like, 'Your life ends - you're never going to be able to do anything again!' And I'm like, 'What are you talking about?'
"Motherhood is the most beautiful, exciting thing, and there's nothing that I feel like I can't accomplish while having children in my life."

Emily VanCamp can't wait to start a family.
The 'Revenge' actress, who has been dating her British co-star Josh Bowman since late 2011, admits she is very broody because two of her sisters are currently pregnant, but wants to wait until the series is over so she has more time to devote to children.
Asked if she has any baby plans, the 28-year-old star told the 'Meredith Vieira Show': "Yes, absolutely, especially when your sisters are having babies you just want to jump on the bandwagon. But I'm just happy being an auntie right now."
She added: "I'm really busy and I feel like I kind of want to be the kind of mom I want to be. With this schedule and playing this very tortured -- exciting to play, but crazy character -- I think I'll let that happen and I'll see where I'm at. They just make me so happy."
Emily already has a very close bond with her nephew Emmett and niece Ivy.
She said: "They just bring so much light to my life. It's amazing."
The blonde beauty and Josh, 26, went public with their relationship in January 2012, but she previously admitted she hates talking about him.
She said: "Josh and I keep it all very separate. I barely talk about him in interviews, to be honest."