Good comments above. Here are my quick thoughts on this one. I think with feedback we have to try to treat others as we would wish to be treated. As stated above, writers here are not professionals and are mostly offering their work for free. If there are little errors - which there always are in my work, because I'm too busy to be careful - then a PM pointer can be useful. But it's a risky thing to expose your work to criticism and I think we all need to be sensitive to that. Friendly, sympathetic, good-humoured comments are always welcome; nit-picky, point-scoring is never worth anything, I'd say. When someone says something nice about my writing, I get a massive buzz. Isn't it better to be a spreader of such joy than a purveyor of misery, discomfort or disappointment? In the end, anyone who goes out of their way to make mean, unpleasant comments to someone else probably needs to think about what it is that they are really angry about.