I'll comm good players, period.
Sure a nice portrait helps, same with a cute or funny name, or a nice glamour. But playing well means you get my comm.
And if you're nice in chat that usually locks in the comm regardless of role.

I have a decent number of commendations for my playtime, I had some 1100~ at the end of SHB. I started maining DRG (previously DRK main from HW-SHB end) and my comms are currently sitting at 2350~, a large section of which are from me just doing DRG stuff in dailies. Some are from me leveling healers and tanks, sure, but nowhere near the bulk of them since the start of EW come from those roles.