You be surprised. I know a gentlemen who's had his pictures stolen, from another forum, and printed in a book, by someone else! How's that for the ultimate rip off?
There is nothing to stop people taking pictures from the internet and claiming them to be their's, nothing to stop photoshop, no one has even suggested adding he date and time feature to the pictures to make sure they were taken within the competition time frame.
I've got plenty of personal pics that I could slowly dribble into the competition, as I'm sure many others have, and to think that it could never happen, or won't