From Bruce Schneier’s “The Psychology of Con Men” (Crypto-Gram: 15 November 2008):
Great story: “My all-time favourite [short con] only makes the con artist a few dollars every time he does it, but I absolutely love it. These guys used to go door-to-door in the 1970s selling lightbulbs and they would offer to replace every single lightbulb in your house, so all your old lightbulbs would be replaced with a brand new lightbulb, and it would cost you, say $5, so a fraction of the cost of what new lightbulbs would cost. So the man comes in, he replaces each lightbulb, every single one in the house, and does it, you can check, and they all work, and then he takes all the lightbulbs that he’s just taken from the person’s house, goes next door and then sells them the same lightbulbs again. So it’s really just moving lightbulbs from one house to another and charging people a fee to do it.”
http://www.abc.net.au/rn/lawreport/stories/2008/2376933.htm