1. I played with a DM once who wanted to run an Epic level game, but felt that at those levels, actually bothering to stat out multiple enemy NPCs to fight us took too much effort.
So most fights ended up involving one huge monster, or several smaller identical ones, that we'd be expected to pound on until they died. One, in particular, was awful... It was some huge undead worm-thing that took... I forget, somewhere between 500 and 1000 hp of damage to kill - at which point it split into two smaller ones, that each had 1/2 the hp of the big one. Oh, and the SR and saves on this thing were so high, magic was effectively useless.
I think once it had split into eight pieces, they finally died when brought to 0hp instead of splitting further, but by that point, we'd spent like 2-3 hours real-time involved in the most boring RPG combat I ever participated in.
2a. A DM I played with for much too long (actually the 2nd 3E game I played in, so for a while, I didn't know better) was too lazy to design decent encounters that'd challenge the players in intelligent ways, so instead, he simply jacked everything up: He gave everything max hitpoints, geared up almost every enemy we fought to be a melee tank, (aside from the occasional arcane caster with sky-high spell DCs and no tactics), and cheated/made arbitrary rulings to stop us from using high-end magic to turn the combats into something other than a slugfest.
2b. Same guy decided to throw a CR16 Nightwalker (max HP, naturally) at a 11th level party with either 1 or 2 +3 weapons. (this was 3E, not 3.5, so it used the old-style DR)
When I had a wizard I was running break out the Antimagic Field (it had a ton of Supernatural abilities - including its DR - that'd get cancelled out by that, and we didn't really have a lot of magic items, so it'd not hurt us too badly), he decided by DM fiat it didn't work that way, even when I showed him the text in the MM that spelled out how Supernatural abilities were affected by antimagic - and went on to break a +3 sword and kill one of the PCs using the thing's death gaze, before realizing that we were completely outmatched, and starting to play it like a big dumb combat brute insetad of using its remaining magical abilities.
2c. Same guy, last story. My main character in that game was an elven rogue. (I ran the wizard I mentioned above as an NPC in one session) He had a natural Dex of 20 (overall stats Str 15, Dex 20, Con 13, Int 16, Wis 13 Cha 8 - excellent but hardly anything game-breaking, especially since this was early 3E and he was staright out of the PHB) and ended up with a Gloves of Dex +2 along the way. (this was at, I dunno, 6th or 8th level - totally appropriate gear)
The DM - who as I said, tended to run nearly everything as a simplistic slugfest - couldn't deal with a well-played rogue character, and he started blaming his failure to challenge on how "broken" the character was, and how "broken" it was for him to have the gloves.
So opponents with arbitrarily high listen and spot (to make sure I wouldn't be able to sneak up on them) started to crop up, while I would sometimes fail to hear enemies clad in full plate well in advance, and every BBEG we encountered after a while was immune to critical hits and sneak attack.
Things didn't get completely absurd, though, until his obsession with the gloves reached a point where he started to actively try to destroy them. He began by house-ruling the Fireball spell so that it'd require your items to save every time you were hit by it, and not just when you rolled a 1 on your Reflex save.
He then cooked up an enemy spellcaster with fireball at a DC of 25 or so, and had him cast it at the entire party through a tiny opening as we were exploring an enemy-held building, and ruled that we didn't even get to roll spot or listen to notice the ambush.
Anyone else see the flaw in nuking the whole party to get a rogue with a Reflex-based spell? My character was the only one to make the save - I ended up getting something in the low 30s, so he could not claim I failed it without making it blatant he wasn't even trying to play fair - and everyone else in the part ended up losing magical items to the fire, while the party Wizard came within a few HP of dying outright.
But it didn't end there... A few sessions later, after he apparently dropped the whole nonsensical idea he actually allowed my character acquire (along with a bunch of other gear for the party) a pair of Gloves of Dex +4 - that turned out to be Gloves of Fumbling.
Problem was, he'd freakin' forget about it in non-essential situations, so the fumbling effect was so intermittent, we were unable to figure out what was causing it for something like a couple of months of real-time. It came to a head when he remembered about it in the middle of a key fight, on-IIRC - another damn plane, with absolutely no way to get them off, and I just blew up at the idea that over weeks of game-time my fastidiously neat and clean character hadn't noticed, until now, that he wasn't able to take his gauntlets off.
His defense was that he didn't imagine I could think he could possibly have given me a benign item, after all the trouble he went to with the +2 gloves... My response was that I guessed I shouldn't have given him the benefit of the doubt and assumed he'd simply realized what he was doing wrong and decided to stop being a complete $&%@#.
Needless to say, the game eventually fell apart...
