A while back, Prince performed in my city. After the "big" concert, he visited a very small club to hang out, and he decided to take to the stage just for the fun of it. Now, for anyone who doesn't know, His Royal Purpleness absolutely hates having his picture taken while he's performing - the flash really bothers his eyes. Before he started playing, he announced this and said "So, please, no photos." Naturally, several people chose to ignore his request.
Now, it's a matter of opinion as to who was the SS here - Prince or the fans who took his picture without his permission. Me, I'm on Prince's side - he very politely asked people not to use their cameras, and they did so anyway. The worst part, however, is that one of those people managed to make some money by selling the picture to the local newspaper the next day.