See, the problem is that when I dislike a game, it kind of disappears from my memory pretty quickly. I only remember games I enjoy (some kind of mental defense against game-related suicide), unless the game was bad in a comical way.
Although, I can say I was extremely disappointed by UFC 2009: Undisputed. I'm sure people who don't do martial arts could enjoy it, but as a black belt who's studied 3 different martial arts (including Muay Thai and Brazillian Jiu-jitsu, so this is an area of expertise for me) I was shocked and enraged at how utterly unrealistic the game was. It was still fun, but I expected a martial artist's cream-dream.
Also, Dragon Age. Again, I enjoyed it immensely. But the story wasn't nearly as good as I expected it to be, and it didn't take me long at all to discover that they'd just taken Star Wars: KOTOR and slapped a fresh coat of "Fantasy" over the old coat of "Sci-Fi"