Changing rules to win ?

Why is it that Joe Devon, of a href="http://www.josephdevon.com," rel="nofollow"http://www.josephdevon.com,/a had to change the rules of his "The Great Typo Hunt", just to avoid having to award a measly $5.00 gift card to a reader that found a typo in what Mr. Devon had typed ? Originally, his rules stated that if anyone found anything he had written that had a typo in it, to email him, and the finder would be given a prize. When someone found a typo in his website content, and informed Mr. Devon, he changed his rules on the website to exclude the mistake that was found. I guess his books aren't selling so well because he can't afford to send the $5.00 gift card to the mistake finder. Don't you just hate cheaters?