Thus far, I've had pretty gotten decently geared and intelligent groups, not really encountered that many problems (only one in fact, which I'll elaborate on shortly). In all honesty, before LFD came around, I'd never be caught dead doing a PuG or anything that doesn't involve guild mates or their direct friends.
I've only had one issue in a PuG where I was vote kicked by the three DPS for pulling too fast (I had around 45k buffed HP and the healer had around 28k mana, never dropping below 85%). The healer did not complain once, and furthermore the DPS did not communicate their problem with my pulling too fast (even though I held aggro almost perfectly) and just decided to kick me out half way through the Heroic without saying a word until the moment I was about to be kicked.
Their words? "Lol ur a jerk dude, slow down and stop beign an elitizt" or some such stupidity.
I was so blown away by this I decided to not tank another PuG for nearly three days.