What constitutes a "good" practitioner of any discipline? As offered above, passion to be sure, but also integrity, skill, talent specific to one's medium, creativity and imagination. Nearly everyone recognizes incompetence, many recognize solid performance, a few recognize all the preceding plus a giftedness way beyond the ordinary. The issue that is more german is who gets to determine the competence of the work in question. When I ask for a critique by posting to that gallery, I am professing a willingness to consider whatever is offered. Unless I request a review by a specified critiquer which isn't an option on this (or any other site I know of), I have to consider all posts.
Why would this question constitute a "can of worms"?