Kaspar,
That would be pretty cool. I've got no idea how to begin.
I've modifed the text files so that the Avatar sections add "*****G-RATED PICS ONLY******" yet indeed, many people do not read or want to screw with me.

So then I usually go in and replace it with the question mark face....then PM the user.
Not so bad now that the pics update with the profile. The used to be stored in the posts and had no way to fix them (as I wasn't DB savvy at the time).