Penn (of Penn and Teller) says that there are two kinds of magic tricks. Ones that are so unbelievably easy you cannot imagine the method, and the ones that involve so much work you cannot imagine the method. One time, he saw a magician perform a trick and guessed he had been in prison, because the amount of work it takes to prep it is so long there's no way anyone else would have the time.
and Teller says that the secret to a good trick is to put in more effort than the audience thinks any same person would. The Prestige has tricks like this (some totally fictional, some based on real magicians).
