I've played every DPS at one time or another, except DNC. I play with animations on, and have a decent eye for detail. If the pulls are melting, the DPS seldom gets hit or the hit seems to be intentional to do more damage and they make up for it with Bloodbath or something... yeah I comm the DPS. At least if they don't leave the dungeon right away. A LOT of people leave dungeons before I can hand out my comm.

Or if the Healer or Tank are exceptionally bad and the DPS did alright, then I give it to them, particularly if I still need my weekly commendation challenge log EXP.

If no one did well in my eyes, which is rare, or if people tried to pick fights with one another without adding anything constructive, I generally comm no one.