Simon Cowell is one of the nicest guys in showbiz.

The music mogul's good pal Louis Walsh - who has been friends with Simon for 15 years - has insisted the critical 'The X Factor' USA judge is much nicer than his nasty TV persona and is really great fun.

He told Irish chat show the 'Late Late Show' recently: ''We're best friends. He's such a nice guy. We worked together on a daily basis for fifteen years. I know him really, really well. He's such a nice guy, he's nothing like everybody thinks he is. He's great fun.''

Louis isn't Simon's only fan. The 52-year-old SyCo boss fuelled rumours he is dating Carmen Electra after he was spotted ''making out'' with her in the US last weekend.

Simon enjoyed a romantic dinner with the former 'Baywatch' actress at Hollywood restaurant Cecconi's on Saturday (22.09.12), where the pair were said to be ''holding hands and staring into each other's eyes''.

A source said: ''They were getting very cosy. They were holding hands and staring into each other's eyes - and then they started making out.

''They were with other friends at the restaurant but didn't seem to mind.''

Simon and Carmen were also seen flirting when she appeared as a guest judge on 'Britain's Got Talent' earlier this year.

The insider added: ''Carmen loves hanging out with Simon. They're having fun.

''She is getting back in the dating pool and Simon treats her very well. It's all very laid back at the moment but they are both enjoying themselves.''