I usually have an extremely high tolerance for people in LFR. Low DPS, excessively talkative, stands in fire, low iLvl - I won't ever initiate a kick if you're one of those people, although I may vote if someone else does, depending on how bad I think you are and whether I think you're trying your best.
Today's LFR, however, brought an absolute @#$%head healer who missed the mage table at the beginning (even though it was announced as a raid warning through someone's mod) and then proceeded to complain after every pull that he was out of mana and refused to heal.
I was, quite frankly, surprised this priest managed to last in the raid all the way until the first boss, especially as he took on a rogue that had told him to shut up, apparently not only arguing in raid chat but also whispering the rogue and several others to demand free mage food.
Right before the boss, one of the mages finally put a table down, so the priest got his way... except I chose that moment to initiate a kick.
Totally worth the couple of minutes' wait for another healer. Totally.