A good player... - doesn't get an elitist attitude on every single player he meets just because someone doesn't use things 100% perfect. - adapts to the situation accordingly, with clear objective taking priority, depending on how his job-related kit allows it (like RDM being able to cast emergency heals/rezz). - isn't defined by how much skill he's got in terms of clearing difficult content while being sour and brash to other people but how positive he can interact with his teammates. I'd almost add that a good player sometimes needs to stay silent in cross-world parties so things don't go out of hand.