Fair warning: this is sorta a mini-rant because I totally empathize with playing in a bad group and I'd like to vent a bit myself...
I actually bailed on my group about two weeks ago because of one particular person. He was the DM in one game and a player in mine, but he was an uber-goober and his issues go well beyond the game.
He ran a pretty lackluster game, for starters. The narrative was just flat and boring with no real connection from session to session and the dude just didn't know anything about the rules. This, and he refuses to prepare before game, insisting that he "can wing it." So he's trying to figure attack bonuses and save spell DCs on his fingers when we encounter a 5th-level ogre barbarian. He'd also tell players pretty brazen stuff like, "By the way, the thieves' guild is angry at you so they kidnap you in the middle of the night. No one can do anything about it, so don't bother with Spot or Listen checks." (Yes, that's a direct quote.) His style was very ham-fisted and adversarial, and he tried to "win" by screwing over the other players whenever they derailed his flimsy plots.
When he played in the games that I ran, he shouted over all the other players and insisted that they had to do what he said because he was the paladin. Whenever he failed a roll, he'd flat-out ask to re-roll it "because he didn't make it the first time." Yes, this dude was ballsy enough to flat-out fail a roll and ask to reroll until he suceeded.
He also has massive personal issues, the biggest of which was his hygeine. The guy had a massive case of troglodyte stench and insisted that we play in his apartment (which stunk like him, but it was worse because it's a tiny enclosed space with no ventilation.) He'd also want everyone to pay him approximately $10/session to cook dinner for the group, and he'd cook stuff like a box of rice-a-roni and pink steaks (and insist that the players bring their own snacks and drinks to share too). He had disturbing personal issues with other people in the group and at the game store we frequented. I'm not going into details because it's pretty disturbing, but suffice to say, this chap certainly has a way of clearing a room when he enters.
The great majority of sessions devolved into some sort of tension over either the game or his personal issues, so I stopped going. I play D&D for fun, not to help someone exercise creative narcissism or to work through their control/self-image issues. I'm not a therapist or a "life coach" or whatever the preferred title is. If the game isn't fun, I stop going. But I do try to be constructive about it and part on friendly terms whenever possible.