I think its the decision making skills. Anyone can fly one of the things, the people that go up, come down, have no dents in the aircraft are the good pilots. Its the people that think they are god's gift to aviation that I think are bad pilots.
Decision making skills should become better with experience, so I would say that is what makes a good pilot. People that come on these forums and actually learn from others experience.
I'm just a newbie in the working field so thats just my humble opinion.