Ok to be honest sometimes I have been really bad GM. Once I sucked because group was way too big for my ability to handle. Sometimes I lack inspiration, or pull themes that players don't like at all. Sometimes I end up hating some character and without even noticing make that one's life hard.
I have been bad player too. Not interested really about game. Being totally passive agressive about and half-slept through sessions.
Most of the time I am ok with both.
However I'd had questionable pleasure to play with people who are most of the time jerks in and out of game. Selfish, whiny, greedy, griefers, sometimes all that plus bonus behavior like arguing with dm about rules and story. They were even worse when being dm:s. But at least 2 of them had ability to act nice like 2 sessions of being dm, and max 4 as player. So they sometimes worked fine with one-shots.,
Then there was major roleplayers. Yawn. DM who allowed and expected players to play out all the shopping and bargaining. And there were whole sessions of that. Additionally some of players constantly played characters that didn't want to go to adventures or do other dangerous stuff. Additionally some favored pc:s always had their secret projects, not shared with pc:s. When it was not shopping, there was 4 people playing solo with dm about their character stuff, each just game in different room taking 20min-over hour. And whole session was like that 4 people playing solo and 6 other people mostly waiting.
One of them was horrible spot-light hugging drama queen, who liked to talk with all evil things, especially if her boyfriend was gm. When she was gm she expected everyone's characters to fall charmed by her (awful) npc:s. Mind you, without actual charm-spells, she was relaying on her own flirty charms. She was found of games like Amber, Earthdawn and Forgotten Realms when it was D&D. Her unbeatable DMPC:s including known ones like the Seven Sisters, Mystra and other gods, elder amberites, which she played really bitchy even men. Her plots were very pre-written and she didn't like pc:s to get out of line. And she had favorite players. Then again whole group had that issue. Games weren't always that bad, there were moments of fun.
I had GM I really liked otherwise. But he had that flavor of the week thing. Always when he read new book, or comic or saw a movie with something cool, he almost directly ripped it to appear in games. Plus he had certain number of really obnoxious npc:s. Most of them really powerful, evil, bitchy, ubersexy spellcasters. But he had great imagination, sessions were almost always fun and you could kill his horrible npc:s. He wasn't very protective of them.
Back to teen-gaming years, there was 3 occasions of misplaced falling in love. That was annoying and ruined gaming group 2/3 case.
My current group bad dm issues are basicly two. He tries to force group to avoid danger when he is DM, bit like he tries to play his characters, when he plays. This lead to boring run-away from encounters sessions or waiting for enemiies to assault our home village -- 4 sessions of waiting. Then we quit the game. He doesnt do that always, he is actually quite good when he is running a module, but he can't handle his own adventures. And you can't die in his games, and he changes his monster's hp:s and other abiilties on fly.
Another typical issue with that group is that certain player and dm himself intrupt the game to tell about other games, because some other people in that other game years past did something so COOL. Hate it hate it hate it.
Yet I am still playing with this group, they are nice people and some sessions are good.
Then there are some dm:s that are usually good, but sometimes started really bad game/session.
I had quite thick skin for sucky gaming. Only during few last years I've come to conclusion that nothing special to do, is actually superior to bad gaming. Especially after worst rpg experience of my life. Nowdays I only have 3 groups, 2 of them share people. I don't get to game that often. But that's ok. If I dicount jerks, I did get to meet all kinda interesting people. Even if rpg preferances didn't mesh well, or expectations of gaming weren't met, socially I still feel I gained something good.
He was only a mild fun-drain during the game that night, but it was overall not a good experience for me. I'm not really sure what to do in cases like that. If someone is being nasty to me (last happened nearly 3 years ago) I can kick them out no trouble, but this was just an un-fun player with a very thick skin. With my 'work' hat on I've no trouble being stern with people, but with my 'social' hat on I can find it hard to be assertive (which may be news to my players who read this board, but if you'd been at that Monday game you'd know what I mean) or to hurt someone's feelings.
