I asked this question of my professor and mentor Robert Godfrey:

Remember when I showed you a satchel of my latest work and you told me I was a “good” artist? I have wondered ever since, what you meant by that, exactly. Is it about skill, technique, execution or exploration of a subject, productivity? Will you clarify?

His reply follows:

“Maybe a good artist is someone who has a kind of an innate knowledge  of something she can experience and express plastically (visually) even though they, themselves, may not be aware of (sort of that period between dreaming and waking up). And a certain viewer or outsider (if not the artist) picks it up in an “ah ha” moment.  As I did.  Your drawings told me something about you and bridges that I didn’t previously see or know.  

Don’t think this can be taught – some have and some don’t.  I cannot “exactly” describe because good art is too elusive and slippery for “exact” analysis.  Like poetry, music etc.  But “good” art certainly has nothing to do with skill, technique, execution, exploration, productivity …. the totality of something that resonates can not be picked apart, though certain things you mention may factor in.  

I think it was Virginia Woolf who said something to the effect that she had to distance herself from consciousness in order to write freely.  

So I wouldn’t worry too much about it all.  Just keep doing what you do.”
Thank you, Bob.