Usually when I queue I let everyone know in the beginning that I won't be picking up the slack for others, I let them know where the enmity bar is, how I will be tanking, and to ask any questions now before we run through. The success rate of this is above 50% but you do have your asshats but at least if I can teach 1 person out of the group to be a more aware player I think I've done more than I can be ask for.

Everyone wants smooth runs and to enjoy the game, I think "community" is missing from MMO's now - not many people willing to help but rather just rage from 0-60 instantly, especially from the DPS.