"The best kind of criticism is to take a completed work, improve on it, and then tell what you did." - spurlock5 Once again, if you'll excuse me being pedantic, that is not criticism so much as mentoring. True criticism is not really intended to help the artist at all. It is intended to help the viewer/reader. That is certainly the case with professional criticism, it may be a bit different in practice here. But we are dealing with someone who is allegedly coming from a professional position. The best kind of criticism, as I have seen and read it, is criticism that opens up a picture to interpretations you didn't realise were there, and brings you to an awareness of the details of the structure of a work which again, may have passed you by. Of course, in the case of an artwork that is totally shallow, the critic can have nothing to say other than to point out the emptiness of it all. Even that can be informative. But this is meant for the reader, not the artist.