Durumu was one of the bosses I would really take my time and teach the LFR team about, no need to be a dick to anyone. I think it's pathetic when people get pissed off due to a few out of a massive group not understanding a fight. Not everyone started playing wow when you did, for all you know it's their first attempt on the boss and even if it's their hundredth attempt you should take the initiative and explain it to them, mark yourself and have them follow you.
If you really want an increase in the performance of players in random dungeons and raids you need to start being empathetic and teaching them strats, then one day you may get lucky and wind up in a group with a bunch of people who know the fight and have a positive attitude. I mean it's a fucking video game if you're not playing it to relax and have fun you shouldn't play it.