They've been scraping the barrel for celebs for a few years now. Then you get all the fuss when better dancers don't get the votes and end up in the dance off whilst rubbish dancers are kept in (because they have a fan base and a personality). Then you get the bullying accusations, lewd comments by ex contestants hanging over it, judges favourites, comments about Shirley not liking certain women etc.
The X Factor went the same way before it was binned.