The problem I've seen is that people bitch, moan and rage. They are never constructive in their critisism.
I was doing heroic EoA with... noobs, ok, I'll be honest. We wiped on Serpentix because not enough trash was killed.
What I could have done was to act like this: "omfg wtf you fucking suck im carrying your asses. fucking unistall the game!!"
Instead, I said "we need to clear more trash".
I did end up leaving, but that was because people were slacking/being semi afk
I also tend to dislike statements that aren't angry, but more like "you suck and I don't"
Like the dungeon I did with my rogue. Normally, when I play with my rogue, I use interrupt pretty much on CD. This time though, the tank was actually using
his interrupt on CD too! I've never seen that! Now, that led to me using my interrupt on a spell just when he used his. He also had an addon which let people know how good he was at interrupting (the one that announces your interrupt).
So the tank then said something along the lines of "being so happy to play with useless rogues who don't know what interrupt is", instead of asking "rogues, can you interrupt too?"
And if you think you're such a fucking prodigy at this game that the unwashed masses in random heroics should be eternally grateful for your calming and inspiring presence, get the fuck out! You're not going to make people improve by yelling at them. Go do your daily heroic with your guild, or does no one want to come with you because of your attitude? I'd rather do a heroic dungeon with a 100k dps than someone who's at 500k and thinks he's the best player ever and keeps on yelling and raging. In fact, you're too good for WoW, aren't you? You should quit and cure cancer because you're such a skilled individual