Mariah Carey was a 'Nightmare to Work With' on American Idol - Report

Now that Mariah Carey is officially the new American Idol judge... let the mudslinging begin! TMZ is reporting that Mariah was a "nightmare to work with" when she was the guest mentor during Season 7.

I believe it! Mariah is a diva and she will let you know. Good luck Nigel Lythgoe! This is going to be an amazing Season 12. Long Live American Idol! I love this show!!!

From TMZ:

Mariah Carey was a "nightmare to work with" during her brief stint as a guest mentor on "American Idol" in 2008 -- this according to sources on the show.

Sources tell TMZ, Mariah -- who made her mentor cameo on "Idol" Season 7 -- was incredibly late for her shoot at the Beverly Hills Hotel," not very nice at all," and ridiculously nitpicky about tiny details.