I always comm the other dps unless they are just bad.

smns who don't dot or bane, brds who don't use songs, ice mages or mages that have no concept of their rotation after about lvl 50, mnks/drgs who still single target on humungous pack pulls, nins with no ninjustsu or the dps who spend half their time in auto-attack only mode, yeah I see you lol. Sometimes its obvious as well when a tank or healer is duoboxing, no ones getting a comm then.