[Yen]

Good staff members always hold a neutral point-of-view as far as players are concerned, don't care about rights (as long as they have what is required), and deal with players in a polite manner. They don't try to instigate fights with other staff members, either.
Oh yeah, being good at their job (and doing it) is a plus.

People should be fired for repeatedly breaking rules (more so if it's the same rule over and over), fighting with players, not doing their job (or doing it poorly), or leaking the server's material to others.