for me commendation depends on the run.

Normal run, nothing happens out of the ordinary and everybody does their part then according what I play I do this : tank<==>healer and dps<==>dps (in 8 man its healer/healer and tank/tank)

Then you have your troubled runs. Then I got for the most helpful, efficient, patient.

Rarely I don't give any commendation, but happens when horrid run and no one even answers or try to solve the problems.