On one of the other photographers communities that I'm on, they have kind of a system for letting people know what kind of criticism you want when you post up pictures. I mean, sometimes people post pictures just to share. Other times, we are using this community, and others like it, as a tool to help us grow and develop as photographers. I'm thinking that more often than not, most of us fall into the latter category, but I don't like to assume. And if you're like me, you don't want the sugar-coated criticism. You want to hear the real deal, the no-holds barred, "this is what's good about your photo, this is what's not, and this is what you could've done to improve it." If I learned anything from filmmaking classes in college, it's that the best criticism is usually the most honest.
So, what I'm thinking is that in the subject line of your post, maybe we should include whether or not you want your picture critiqued. This way, those of us viewing the pictures can differentiate between the, "I'm posting this because I thought it was cool and just wanted to share," posts from the "Hey, I liked this, but I'd like to know how it could be better" posts. So, maybe just put "Criticism Welcome" or something similar in the subject line, so the rest of us know if we should be looking for ways that the shot could've been improved, or just enjoying your work as is.
Also, as deinemuse mentioned, posting your camera's basic EXIF data isn't mandatory, but if you do want criticism on your photo, it could help give the viewers some valuable information on how the picture might be improved.
And please don't misunderstand. I'm not saying that anyone should rag on another person's photos, or simply say "that shot sucks." I'm pretty sure that this goes without saying. Be nice, and be constructive, but be honest, if that's what the poster is looking for.