The former Spice Girl will be seen on tomorrow night's opening episode, as auditions move from London to Manchester.
Speaking about sitting alongside Mel B, the judges revealed how her honesty often led to problems!
"Obviously there are moments when the problem is she always kind of tells the truth and you can’t knock her for it," Tulisa explained. "So there are moments when you’re like, do you have to be that obvious?
"But at the same time she’s saying the truth, so I think you’re either gonna love or hate her on a show like that."
Louis agreed: "She’s just saying what everyone is thinking at home. She’s very honest, that’s why she’s Scary Spice!"
Other guest judges set to appear on this year's series of the show include Geri Halliwell, Rita Ora and Leona Lewis.