I always make sure the game is REALLY good before I buy one. So I have not come across a game that is really crap. But I lent 'Singles' from a friend and it was really boring. And when I say really boring I mean really boring.
I don't even play a lot, especially now when I started to concentrate on Linux. And usually I only play games which my friends suggest.
Ok, I beta tested Lineage 2. It was just totally boring. Well it had cool animations, textures and graphics, but like no idea in it. I hated the one-on-one combat system, totally uninteresting in a game which needs action. The quests were boring too. Not a nice game indeed.