I got kicked out of a Hammer Station 55 once on my Mercenary, for taunting off the tank.
Just read that and think about it for a minute.
Always funny when this happens (not the kicked part, but the blame on taunting). Occasionally it is true, I've had shadow dps taunt off me because they thought they were helping.
I've yet to be kicked from a group, but if I kick someone it tends to be for ignoring the group, refusing to change bad behavior they are called out on (ninja looting, purposely pulling mobs without reason), or an overall bad attitude. I've kicked both healers and tanks (I play a healer or a tank depending on who I'm on) and finished the run with a companion because they did something the group was not willing to tolerate.