I agree with you John that some pictures that were never intended to be "art" can come to be viewed as such. The intention of the creator is not necessarily the only consideration, but it often helps (if the answer is important).
I think the idea of art is a very slippery and incredibly subjective concept. In fact, I think that trying to define exactly what "art" means is pretty pointless. But it no doubt keeps a few philosophers busy, and allows a legion of academics and curators to get away with writing gibberish.