The Final Fantasy XI Addon Expansions - There were three of them, each released about three months apart for $10. They were each quest lines with unique stories and good rewards at the end, but they were really short and the difficulty came more from the tediousness and repetitiveness of the games. Not only that, but I spent $30 in total between the three add-ons, and a month after the third one was released they announced a collection of all three for $5 IN TOTAL.
Mortal Kombat Armageddon - I would never have bought it if my friend didn't rave about it for like a whole week. Then I started playing it and realized that nothing at all appealed to me.
Red Dead Redemption - Another game I bought solely because of the hype. Because there was no way to map the controls to my liking, my muscles had no way of coping with the huge change in gameplay from what I was used to. I barely passed the tutorial section and haven't played it since.
inFamous - Same problem as with RDR: there's no way to map the controls to what my muscles are used to so I found the game challenging solely because I couldn't shoot my lightning bolts.
Armored Core 4 For Answer - Ohmygaw what a piece of shit game. If I didn't pay only $20 for a used copy of it I would have demanded a full refund. It's a great example of taking everything that made a great franchise great, revamping it all, and making it into a piece of shit. Armored Core 3 was always one of my favourite games, but For Answer completely obliterated it for me.
Final Fantasy XIII - I'm not much of a Final Fantasy fan, but I did like 10, 11, and 12, so I figured 13 would be good. I guess the superstitious number 13 did its job here. At first I thought it was shit, and then I thought it was OK, but after a little while longer I thought it was shit again. I still haven't beaten it, but that's largely because the simple thought of playing that game makes me ill. I'm just glad I cancelled my pre-order of XIV before it came out, otherwise I'd have had another game on this list.