I personally think she should have rejected the offer. I'm not a big fan of hers but I think a talented singer shouldn't participate in this kind of shows.
I've read Mariah's been asked to work on XFactor USA and I hope she says NO! Reality tv shows may give you a boost on your career but I've always thought a singer should be recognized for her/his talent & music alone.

Christina: you don't need a tv show to come back. Write lyrics, sing songs and perform live-- that's all you need.