Hmmm, well, I'm not a huge Achievement hunter, I go after some, but am not obsessive about it, so I sadly don't remember many really bad ones, since I typically decide if an achievement is more than moderately annoying I'm not going to bother. The exception to this is games where some kind of reward is attached to the achievement.
I did want to mention a couple of things though.
First off, I think a lot of people miss the point of the "free achievement for turning on the game". The idea behind that is so that game companies can tell how many accounts their game was played by. This is in part how they track statistics as to how many copies of a game they moved, as opposed to how many people played it, for the arguments they make about things like used game sales. They aren't "gifting" you a free achievement or helping you boost your gamer score, and being uncreative, they are tagging you. A piece of info I ran into years ago from conversations with people who were all upset that they couldn't voluntarily remove achievements from their list. Some elitists being upset that having a bunch of games with low scores and completion percentages showing up on their list made them look like bad gamers to their elitist friends, them wanting to display only games they had every, or nearly every, achievement for. Apparently Microsoft at least explained that they couldn't allow people to erase achievements or voluntarily lower their score due to data tracking agreements. I have no idea if this changed as I haven't used XBL in ages (my 360 is gathering dust). It's annoying, but there is a method to the madness, and "lazy developers" is kind of what they want you to think, as opposed to the developers tagging you like an animal. The idea being that without this "gift" for you to register you'd have to actually play enough to earn one of the achievements, when they ultimately want to know as
soon as the game enters your machine and turns on.
Secondly, while not a big hunter myself, I have mixed opinions about what achievements represent. To be honest I think the term should be changed. I find them a good way of telling how far someone progressed through a game and things like that. It comes up rarely, but on occasion it's nice to see if someone who seems to be talking out their butt is telling the truth or not, which can be determined by looking at the achievements for some games that reward them just for playing. When it comes to difficult accomplishments in games, basically a test of skill, or at least dedication and patience, I find them less useful due to ways of cheating/glitching through a lot of the hard ones, and I'm more of a believer that there should be some in-game motivation for doing something other than an achievement. Honestly I'm surprised most achievements that aren't awarded for casual play are so popular because it's akin to jumping through a hoop like a trained monkey for a game developer (and I'd imagine many of them laugh at gamers for this). Something like killing a final boss naked twenty times or whatever, which takes perfect timing... giving you a reward showing you were actually dumb enough to do it. It's even worse when the achievement might be something like actually jumping your character through X number of hoops.
On the other hand, I will say that before my WoW retirement I did pretty much every holiday achievement for an entire year to get that Violet Protodrake. I just noticed at least one person talking about how annoying some of those were... and yeah, I agree. It's one of those times I did something like this because of the reward (which is pretty uber as far as mounts go, since it also seems to auto-train skills, or did) and also because at the time I was with a fairly hardcore endgame guild and we were all showing off to each other, and you know, having what was the greatest prestige mount "ever" at that point a big thing. If I ever returned to WoW i'd be a sad guppy stat wise, and probably see Violet Protodrakes either filling the skies, or being considered a scrub mount. One of the reasons I'll never go back, especially with the people I played with pretty much departed (which is why I quit, I tried to return when Pandas came out... but it wasn't the same).... but yeah... I have had my own bouts of insanity, including one which lasted an entire year.