Grand Theft Auto 1, for the PS1. It wasn't nearly as good as GTA 2.

Buying a second copy of Hitman: Blood Money as a gift to a friend. Never gave it to him and I still have it collecting dust.

I love DBZ to death and even I have to admit Taiketsu was terrible lol

Donkey Konga - thought my son would like it ... not so much

That's one amongst many

Mega Man 2 for Game Boy

Star Wars: Flight of the Falcon on GBA. The first level is alright, you just have to shoot some tie fighters but then the second level is just nauseatingly bad and incredibly difficult. There is a password system but it's just not worth it.

More recently, Titanfall. I really liked the beta but for whatever reason something just felt off when I bought the game. I played it for a few days and never touched it again.

Mario party island tour for the 3DS. I didn't know that they abandoned the star system entirely and went to who could finish first. Also story mode sucked and it just sucked overall

LEGO Star Wars....blegh. I don't understand the appeal of the LEGO games.

Civ Revolution for the ds, but I love it on ps360. Highlander for jag cd is beyond bad.

That's a tough one. The problem is that bad games are usually very cheap, so there's not a lot lost if you get even a tiny bit of enjoyment out of it.

The only one I can think of right now is the Burial at Sea expansion to Bioshock Infinite, which took a messy but enjoyable story and made it messier and less enjoyable. I thought the story was dumb and confusing when it ended the first time...