Thing is that people take up criticism in different manners. Some of us are literally craving for criticism, including negative criticism and especially criticism that gives hint and suggestions on how to improve further work.
Politeness, fairness, objectivity, and being specific (what exactly is praised and what exactly is being criticized and what does the critic think the criticized parts should be like instead) are absolute musts when it comes to reviews and criticism to keep it apart from either praise without further information on the one or bashing on the other end of the extremes.
However, not all people can take criticism, even if it is well intended, positively. Artists and writers invest a lot of effort and time and passion into their work. For some their work is nothing that can be separated from themselves and their own personality.
A critic of course must be able to give his or her free and honest opinion even where it does not agree with the view or opinion of an artist. However, an artist who knows that he or she will feel hurt no matter what about negative criticism of the work he or she put so much into should also be given the chance to avoid such criticism.
If artists feel they are not helped by criticism I think that these artists should, without any need of feeling embarassed about it, have the option to include a line in the post of their image / fanfiction stating that they do not wish for negative feedback of their work. Such artists may need to take into account that this might result in receiving fewer feedback (including mixed one) altogether, but they should also really be given this option to have their feelings spared from unintended violation. Because in so large a forum as the GOF chances are that critics may not always remember who is okay with any kind of criticism and who would prefer to be spared negative feedback I think that the respective line for the later should be included in every picture- or story-post to which it applies and critics should respect the stand of the artists in this case.
