What do you do if someone says that they know how a trick is done?
I ask if they purchased the secret from the trick’s author. If they did not, then I report them to the American Magicians’ Royalty Administration Team, which will hound them until they pay what is owned.
(By the way, all the trick secrets on this Web site are already paid for by Presto. Go ahead and use them as much as you need to — just so long as you don’t reprint them or reveal them to non-magicians.)