Some interesting comments in the first one and I'll check some others later. Thank you! I intend to do some of this very soon.

One idea if confronted with someone who demands you delete their photo (which they have no right to demand), is that I can quickly make a "D" corrected copy of the image, then laboriously let them watch while I delete that image with my Nikon D300. It takes only two presses of one button which they would never see you do, in order to create that jpg image from the raw one. Once you press the delete key while they watch, you quickly turn the camera back away from them and your original is still there. I have done this very successfully. If they want another look, tell them it's gone and none of the others are their business.