So where do we draw the line? Doesn't it all depend on what we find arousing? Your first image, for example, of the bare-breasted beauty spanking her plump-assed friend, certainly excites me, even though there is no copulation whatsoever. The same can be said about a well presented clothed body. On the other hand, some of the pics of asses covered in red pimples may not exactly be my thing (though I can see how others might drool all over them). Or what about my posts? They are made up of words, barely images, though the subject matter is sex. And as far as nudity is concerned, in and off itself a naked body has barely anything to do with sex, let alone porn. Once you put it into the proper setting, it doesn't even need to be naked any more, and it can convey the most perverted ideas.