Well fortunately we have our own scanner/printer so I don't have to worry about going to a kiosk to copy a photo... But if I brought a picture to CVS to copy, and that picture had NO notation anywhere on it that it was copyrighted, and the clerk refused to allow me to copy it because they "guessed" it was professionally done, I think I would have a fit. I am by no means a professional photographer, but it IS a hobby of mine and I take a lot of pride in taking really nice photos, so really, how would a clerk know?
Without some sort of copyright mark, I really don't see how a clerk could refuse reproduction of a photo... if the photographer doesn't care enough about his/her own work to bother putting a copyright mark of some sort on it, then why should I worry about reproducing it? in a similar argument, if I leave my car unlocked and my purse on the seat, if someone steals my purse, I bear at least part of the responsibility because I didn't take even the most basic means to secure it. So no, the "it just has to APPEAR professional" argument doesn't fly in my opinion.