Probably APB, aka. All Points Bulletin, aka. The Game that was supposed to be a GTA/Saint's Row MMORPG aka the game that made it's developers bankrupt almost instantly.
Got into the closed beta and never could bring myself to log in again after my first 3-ish hours play session.
Horribly laggy AND barely running on my computer despite me turning down just about every graphical option even though my computer should've had no problem. Other than that, it was enourmously boring, bland, and nothing worked quite right, from the controls to the balancing.
Also, The Undergarden. Dear God, there is something about this game that annoys the hell out of me. It's just an all around horrible experience, although i know most people think otherwise.
And then there is Driv3r. I looved the first one, i still found good things about the sub-par second one, but the third game was just painful
EDIT: Oh and Special Mention to Rainbow Six (as in the very first one) for PSone. People would argue it should've never been ported for the Playstation, and those people would be right. It just doesn't work.