I think this sort is tiny minority of the folks here. I think just a few glances at the work that some of the big guns here makes us realize that we're just not there yet.
As for the subject at hand. I really don't care about the thin skinned types. If you post up work here for perusal, you would be foolish to assume that someone isn't gonna spot (and mention) that mold line that you missed. If you are too touchy about your work, don't post it.
I'd rather folks tell me exactly what I screwed up, so that I don't do them again. It's why I post in the first place. I'd prefer it over a "great job" because I'd feel good that someone cared enough about me and my work, go give it a look over and give me an honest opinion rather than a generic 'ataboy'.
I think everyone who adheres to Thumper's mama's rule of "if you can't say anything nice, say nothing at all" are doing a disservice to the modelers that now feel ignored because everyone was too afraid of hurting feelings. Ignoring the builder and his work (happens a lot) is infinitely worse than offering criticism. You may hurt feelings if you mention the flaws, if you ignore them, you certainly will.
*steps down off the soapbox*