Britney Spears says the hardest thing about the X Factor USA was "getting used to the boos".

The pop star found it tough to face the audience of the American version of talent show if they disagreed with one of her judging decisions.

Despite this downside to her appointment on the hit singing contest, she still wouldn't change her mind about signing up for it.

“It was hard for me at first, and then you gradually get used to it. It’s hard because they all boo you,” Britney explained to FOX News. “You have got 5,000 people behind you and they actually love everyone. So if you say no, they go crazy.”

The long-standing music industry star will make her debut on tomorrow night's premiere of the second season of the show. Britney revealed a little more about what she is looking for from the hopefuls this year.

"I want them to be able to perform, I want them to feel alive onstage, and of course the voice has to be amazing as well,” Britney said. “To combine all those three things is the ‘it’ factor for me… It’s a thrill and is so much fun when you actually see it. It is just the best feeling.”