In my opinion a good player is simply someone with both the willingness and capacity to learn on his own (mentally and physically).

A player that can follow a guide and clear content is not necessarily a good player. A player that can wipe the party but with every successive attempt will get better is a good player.

As such, "pioneers" are good players by this definition. If they manage to find the solution to the problem of "how to kill this new boss" then they show the capacity to learn on their own.

That being said, using guides and such is a trait of a dedicated and/or respectful player. Playing with a respectful but bad player is still better than with a disrespectful good player...well, most of the time.