If demi comes back with a list of achievements he doesnt like this thread must be renamed: Demis Log.
Gears of War 1: All the multiplayer - Esp. Kill 10,000 Ranked
Gears of War 2: Kill 20,000 Period (they fixed it so you can play single player but even that doesnt help) - Play 1999 Online Games
The Club: Kill 10,001 Ranked (a blemish on what would have been an awesome game)
TimeShift: Leave your Xbox on for 48 hours as Dedicated Server
The Orange Box: Play an online game with 7 of your friends at the same time
Rainbow Six Vegas: Reach Elite (unnecessary grinding - later fixed in Vegas 2 by allowing single player grinding)
Rainbow Six Vegas: Play Every map on Every Mode (this equals to about 57 maps total, instead of the default 8 or so. why?)
Mutant League Reloaded: Play levels 1 through 89 on Black Belt (hardest) (not really crappy, but god damn is it hard, so it goes on my list for ruining my almost 200)
Rayman Raving Rabbids: Get a perfect score on all the minigames (pretty much impossible with how shitty it controls. goes on the list.)
Rock Band 2: Play the Endless Setlist without pausing or failing. Great fucking idea.
Rock Band: Forcing you to play World Tour OFFLINE and WITH FRIENDS. Rock Band 2 obviously fixed this. Now I'm stuck with my measly 200 because I know nobody who plays RB on Expert or Hard.
Kane and Lynch: Reach #1 and #2 on Leaderboards (similar to GRAW, except on a game that nobody plays)
Medal of Honor Airborne: Too many 0 point achievements for doing too much work. "Come in first place on every map in any game mode in ranked matches" - 0 points
Brothers in Arms: Hell's Highway: Making you play on a certain day that happens ONCE A YEAR. Making you play X days and X weeks. Making you play against someone who has a certain achievement. Just all wrong.
Call of Duty World At War: Making you play to 10th Prestiege for 0 points. No???
Bejeweled 2: Reach Level 255 in Endless Mode - takes FOREVER, upwards to 30 minutes just to finish 1 level in the later (re: About 50) levels
Mega Man 9: Clear the Game 5 times in 1 day
Texas Hold Em: Get each type of hand (chances of Royal Flush? slim to none)
Perfect Dark Zero: Just awful, all of them
In general: Difficulties that dont stack (huge no-no), online games that make you grind X kills, play X times, etc.