For me, there's no measure for skill, but there's always someone who can play better and someone who can't.
If your sound is tight with the band, then I consider he/she a good guitarist, it only means that you know your own sound. Because other guitarists just plug and play their guitars and not tune, mix the eq's, fix the level of the effects. For me, if you know your setup, then you are considered a good guitarist.
Well, that's just my basis, what about the others?