[ QUOTE ]
If you're the artist and you're posting your art up on a relatively public BBS because you want attention, then you really have no choice but to take critiques regardless of if you want them. If you really don't want people to comment, don't post it.
As for giving critiques, I say that unless the thread specifically says no critiques, or the person posting it isn't the artist themselves, then it's really of no use to try. If they tell you up front they don't want critiques, then they won't listen anyways. If they're not the artist, they really can't make use of the info. Otherwise, it's open season.
Your opinion is exactly that. Your opinion. It is not fact, nor is it law. It's up to the artist themselves to decide if their art is good or not and they should not be influenced by the peanut gallery's every whim. If you're easily upset by comments from people, then you should seriously reconsider never putting up art online again. The net is a wild and untamed land of aggressive idiots, not a closed viewing hall built to rain praises down on you.
[/ QUOTE ]
I would agree with your response...except that I don't think it answers the question the OP was asking. I think your response would be better directed as advice towards artists who might recieve a critique. In other words, an artist should probably be ready and willing to recieve some negative feedback.
However, the OP was asking what the proper etiquette was for when it is acceptable to give a critique. While the net might be a wild and untamed land...that does not make the sorts of aggressive and viscious attacks that are so common proper etiquette. It just makes them typical.