I've been having the same problem all too often lately, where you're in a group for whatever dungeon, and one mistake is made (whether it be from a miss-target, ignorance to the fight's mechanics, etc.), and someone flips out on them, saying things like, "Thanks for the wipe noob" or "This is a simple censored fight, so how are you failing so epicly?" and other various asinine comments.
There seems to be a trend that those so-called "pros" expect everyone else to be on their level, and simply don't tolerate failure.
They seem to have forgotten that at one time they were no better, and this game hasn't even been out a month!
Sure, perhaps they didn't fail quite so hard, but to declare yourself a flawless individual with a right to look down on those who are not on your level is extremely conceited.
I've been in many dungeons with people who have made mistakes, sometimes even stupid ones, but I remember that I was in there shoes once, and I also understand that the last thing they want to hear is how stupid they're being. How about instead you explain to them, calmly, where they went wrong and try to help them succeed the next time?
I know some people are truly hopeless, but not everyone is. Most people can legitimately improve, if you don't treat them like dirt.
Please play nice, everyone. Remember, you were newbie once too!