Sussing out forgeries demands a lot of skill - sometimes. Other times, it's quite obvious that an autograph is bogus or highly suspect. Recent history offers three striking examples. In 2007, Sotheby's Auction offered for sale the "only known autograph" of George Dixon, a 19th Century Bantam and Featherweight World Boxing Champion. The autograph, in pencil, was on a small slip of paper it hadn't been witnessed, dated or notarized. An authenticator had signed off on it, though it obviously was impossible to verify. After all, there were no other known autographs of the boxer. What could the authenticator have compared it to? In 2006, a well-known authentication company verified that an album page had been signed on the reverse side by "April Chadwick." A skeptic asked, "Has anyone ever heard of a person or celebrity named April Chadwick?" Nope. Turned out the authenticator apparently hadn't compared the signature to any other. H...