Hi Bob,
It is all varieties of a common theme, called social engineering, and if people do not use their wit, you can fall victim to it.
Actually this scheme, it is as old as the way to Rome. A gypsy sorcerer would come to the house and if the master brings money to the cellar it will be ten times as much, but only if he cares to wait for five hours after the gypsy has left. Now he has to go to bed, lay still, don't move, later he will be a rich(er) man. Well we all know the end of the story, the greedy man is left with old newspaper clippings, but for shame is not going to tell the authorities, and the gypsy is long gone.
polonus