Hmm, for DPS:

-Did they have a greeting at the start?
-Is my tank being annoying (start/stop pulls, super squishy/eating all TBs straight, etc)
-Did they stay above me on the enmity list for most of the run? I don't use ACT, and I realize the list isn't a surefire way to view how well a person is doing...but I have been on plenty of runs where the DPS is in the 4th spot, on a boss, with no mechs that would force them to stop DPSing.
-Did they use Peloton? I really love me some Peloton.
-Were they generally nice/helpful? Granted most runs are silent, but now and then people will chime in.
-Do I like how their character looks?

I don't require all items to be ticked, but those are some of the main thoughts that go through my head when it comes to comm time. :3