Games that don't deserve their soundtracks.
I'm listening to the CV: Curse of Darkness soundtrack right now, and I'm only on track 3, and it's already blown me away.
It's completely awesome, and yet I feel sort of empty inside because it's the soundtrack for such a mediocre game..
Actually, it's the soundtrack for a very shitty game, considering the standard that most other Castlevania games have set.
The only other case I can think of off the top of my head is CV: LoI, but I'm sure you guys can easily think of a few good examples..