The singer told Absolute Radio's Rock 'N' Roll Football that he was surprised by Kemp's decision to enter the show.
"Martin's a very private bloke and he's very kind of, he's pretty laid back, Mart," Hadley said.
"To be honest, he loves sitting on the couch with a remote control and the TV."
He added: "He's a pretty laid back kind of a guy so I was sort of surprised he wanted to put himself under that kind of pressure.
"But as he said, I think it was last night in the Diary Room, he said, 'Look, you know, this is the game everyone. Why is everyone getting so worked up?'"
Hadley continued: "This is what I don't understand. People are going in, falling in love after a few days, right?
"And then Prince, I called him Princess Lorenzo earlier on - Prince Lorenzo is going, 'Julie, Julie, you're like a mother to me'. Shut up! You've been in there a few days.
"I don't understand it. And then that girl, is it Danica, and she's bending over and Prince Lorenzo is having a... oh, it's like come on! Come on!"
Hadley said: "Martin is a nice guy. Martin is a really nice guy and that comes across.
"He's laid back and he knows it's all a game. He's not going to play the game and I wasn't sure about dressing up as the Greek god!"
Absolute Radio's Rock 'N' Roll Football with Ian Wright is broadcast Saturdays from 5pm on 1215AM.