Probably my biggest "guilty pleasures" are the two Drakengard games. I love them to death. I recognize all of their numerous flaws and the reviews hit the nail on the head in more than one instance, but I still find them FUN. The first game's totally "out there" plot was something I watched with great interest. It's one of the most all-out messed up things ever. The second game's play mechanics were vastly improved, and honestly that game is the most fun I have EVER had with a DW-style hack and slash-er.
Also, Blood Omen 2. The game was NOT a good Legacy of Kain game, and was often a poorly-written, buggy/glitchy mess. But there was something strangely addictive about its combat and general level flow.