I've noticed a recurring theme in the time I've been playing is to blame the healer.
I've been playing since 2007 and recently decided to level a healer.
Now having first hand experience I can say I know how utterly frustrating it is to be given the blame often for something out of your control.
I've gotten to level 50 on my shaman without heirlooms and one thing that really bothers me is a lot of players tendency to blame the healer, I know it's the same at max level as of course I've played a lot of max level (7 level 90 characters).
We just had a dungeon where the tank in full heirlooms body pulled (zero threat) everything in BRD, he's dying so I put a heal on him and about 4 packs start casting at me, killing me in 2 seconds.
This happens about 5 times in the dungeon, tanks getting pissed off saying I suck, learn to heal etc, and when I explain he just won't see reason, responding with "deal with it" "healer problem" and of course including the childish expletives.
One of many experiences.