I still remember my first run in Hellfire Ramparts for exactly this reason. It was a new instance for all of us, the healer and mage were new to the game and hadn't instanced much (having just hit 59 when the expansion came out in the case of the priest) and the rogue kept berating everyone for not being up to his standard of play. As you might expect, he also didn't seem very good, but it was late and I just wanted to get the quests done.
It was endurable, although not terribly fun. We finally got to the first boss, Watchkeeper Gargolmar, and thanks to some really nice work on the part of the priest and hunter, got him down our first try. He did not drop the Bracers of Finesse, however, and the rogue went ballistic. Note that neither I nor anyone else in the party can control what the bosses drop. While we were discussing if anyone in the party was an enchanter, as no one needed the Light-Touched Breastplate, our rogue went off stealthed, deliberately pulled several groups of mobs onto us, vanished and hearthed out while I tried desperately to keep aggro long enough and not die with enough time for the rest of the party to escape. They didn't make it, and between that wipe and the loss of a DPS, we were effectively done for the evening.
Since I knew his guild reasonably well (I'd been in it) I sent the GM a tell expressing my dissatisfaction with what had happened. I mean, who exactly was he angry at? How was it anyone's fault that the bracers didn't drop? The answer I got back was one of my first exposures to the "It's only a game" mentality, as this is the tell our rogue sent to me after his GM got done ripping him a new one. It was 'uncool' of me to have brought it to his GM, it seems, as it's just a game after all. Apparently it's not just a game when you don't get your drop, but it is when you wipe an entire group over it.