I don't think it's a bad game - it's just... a silly game. Easily one of the guiltiest pleasures I've ever had the, er, pleasure of playing. It's an absolute ton of fun and a devourer of free time.
As for outright bad games, there probably aren't a lot that I like.
Although the first not-very-good games that I still enjoy that came to my mind was Final Fantasy VIII. A nightmare of balance and of just about everything, but smurf if I don't still get a lot of enjoyment out of it. I have no idea why.