I hate DMs that are incapable of doing anything that's not written in the module/rule book. Spontaneity is one of the most important things in a game, restricting that crushes the soul.
I hate DMs that rely heavy on the Nose Ring - IE: each of the players has a nose ring with a mithril chain attached, and if the players aren't going exactly where the DM wants them to go, or DOING exactly what the DM wants them to do, he gives it a sharp tug to make then do what he wants.
I hate players that assume that every DM hides behind his screens and simply makes up crap to suit his own agenda.
I hate players that need to build that perfect, un-killable, impossibly powerful build from a vast menagerie of web-sites, and books/tomes/magazines, so they can say "Look at me, I'm 3rd level and have an armor class of 107!"
And by far, most of all: I hate players that think the work and effort of the DM simply doesn't matter, at all, that the - in some cases thousands of hours - the DM has invested to meticulously create a world, the continents, nations, forest, mountains (etc etc) and inhabitants, guys we're talking creating a frigging planet from his imagination, then taking the time to put it on paper - deserves no credit, and he is actually openly sneered at for daring to claim it is "his" world, and his is the final say upon it.
On Stump:
Along the lines of my last "hate" I have noticed one recurring sentiment that seems to come up on almost every thread here, seemingly regardless of the subject of said thread; that invariably there is open contempt for the DM (or even the concept OF a DM). I mean real heated, harsh words, and in some cases maybe even a touch of hatred. I guess I don't understand that. Yes, we've all had that bad DM and that bad experience... apparently quit a bit more bad than good... but for me? As a player? Part of this genre I enjoy the most is not knowing everything that's up my DMs sleeves. Not knowing every conceivable rule or trick. I need that sense of mystery, and honestly, I am not interested in the "we're all the DM at the same time game", not even a little. Too many writers and the story starts to unravel. Hey I've seen it. DMs that play without screens, with his rolls and the sheets of paper with his stats and details sitting out in the open for everyone too see. DMs that seek the approval of their players before he makes virtually any decision of any kind, from something simple to the significant. Where's the mystery? Where's the sense of wonder? Why even bother? If I, as a player will dictate the game TO my DM, and know everything he is going to say, and do - why on god's earth would I play? I wouldn't. And while I cannot tell you what you will think and do, I strongly suspect most of you wouldn't really enjoy that kind of a game either. I think what it boils down too is not every player should be a DM - and a lot of the hating I have been reading since joining this community is likely towards those players that probably shouldn't be DMing. The DM should be that guy or gal that has the knack for it, and if the DM sucks, then go back to playing.
Off Stump