One of the unintended consequences of the boom in online art sales is the proliferation of fake works. Patricia Cohen has an excellent piece in the New York Times outlining where the real trouble lies, not at the top of the market but much further down:
Art is legitimately sold on the Internet at a wide spectrum of sites, including those run by individual artists; established galleries that have expanded online; and new galleries that represent the work of emerging artists. A byproduct of so many reputable businesses’ selling art through the Web these days, experts said, is that it has become easier for those that are less reputable to pass off forgeries.
Fakes can take many forms. Most common are unauthorized reproductions that violate an artist’s copyright or trademark. Other times the reproduction has been authorized, but someone adds the artist’s signature — either forged or copied — to transform a cheap poster into an expensive “signed” limited edition.
Finally, there are out-and-out forgeries sold as the work of an artist.