The people that think they are spying on their campsites really don't understand them, and have definitely never used one.
As has been said, after about 50 yards away, they can tell what kind of camper you have. Most likely.
They do an excellent job at landscapes, with their wide angle lense. I like them as an amateur photographer, since they can add a great perspective to where you happen to be camped.
The noise from them is extremely annoying though. I do not like that at all. So, I usually don't fly my cheap crappy one when anyone else is outside.