The contestants go through several rounds of producer auditions before meeting the judges. There wouldn't be time for the judges to see everyone.
I have seen Nick live, he came across very well, not afraid to give his opinion even if others didn't agree. He is'nt the reason XF is failing so badly this year. Cheryl brings nothing in my opinion, she's only there for self promotion. I think Rita will be a good mentor as she was on the Voice.