It takes a lot of courage to post or hang ones work and if the work gets verbally trashed, that person may get discouraged. I always ask: Who am I to be criticizing? If the person honestly doesn't know that the work isn't up to par, it is still not my job to point that out. Unless someone asks me for my opinion. That said, I have seen some cringeworthy tops which were bypassed quickly at a show - without comment.