In every MMO I've played, the tank is the first to have blame placed on them in random groups, I know, I've always mained a tank.. Next is the healer, then the DPS that keeps dying or taking too much damage, and down the list it goes.

If people would be more open to the help given to them, and the people giving suggestion/help, a little more tactful in their presentation, dungeons would be a different place, but people too often jump straight to accusation and anger.

A conversation that should be;

Player A: So I see you are using Fast->Riot Blade, it would be more beneficial to use Fast Blade->Savage Blade->Rage of Halone, as well as throwing a Flash in from time to time, that way the healer won't pull aggro as often.
Player B: Oh, I'll give that a try.

Tends to be;

Player A: Hey, don't use Riot Blade and use Flash idiot!
Player B: Don't tell me how to play my class!