I cannot think of any game that I bought that I hated.
Games that I regret buying at full price for various reasons:
Dead Space 3 - An average 6-8 hour game with no real replay value.
Assassins Creed 3 - The campaign was a good length, but I feel bad for supporting Ubisofts yearly sequel policy.
Mass Effect 3 - Just a disappointment overall. The game-play itself wasn't bad, but it was the worst out of the three.
Fallout New Vegas - I love the game, but at release it was such a broken, buggy mess. Once they fixed it, all was good.
Tomb Raider (2013) - A very good game, but like Dead Space 3 it has nothing to really go back to.
Dishonored - I liked it overall, but found it very frustrating at times, and not worth the full price.
Dragon Age 2 - I don't hate the game, but I felt a little cheated upon release considering all of the hype Bioware built up.
Transformers: Fall of Cybertron - Not a bad game, but nothing special. Again, once beaten it had nothing to replay.
'Splosion Man - Although it was very cheap (160MS points) I have never actually really wanted to play it.
Max Payne 2 and NeverWinter Nights 2 - Both bought on Steam sale and I have never completed them.
Alan Wake (PC) - I played it on the Xbox, bought it during a Steam sale and have never completed it.
Okami - Nice art style, but I felt that it was a very boring game.
Beyond Good and Evil - Interesting idea, but another game that I found boring.