Ive always been a student of the major art forgers from the mid 1700's on up. Art forgery has always been a "high art" and during the last century the most famous (IMHO) was the faking of the "early Vermeers" by the DUtch artit Han van Meegeren. His work was so good to the critics of the day, that he was accused of selling "NAtional Dutch Treasures" to the NAzis, specifically Herman Gowering.
At the end of WWII, van Meegeren was in such hot water with the Nuremburg tribunals that he was required to actually paint a "vermeer" in orser to save his own ass. (He was on trial for collaboration). When in all reality, Van Meegeren was frustrated throughout his life at the Art juries and academies that selected works for major shows. He was often passed over and to prove that he was an artist of merit , he began fakind works of several old masters with Vermeer as his most frequent target of his form of admiration.
Several other artists like de Hory and Whacker and a few others had had brief but spectacular careers faking works of post impressionists and expressionists .
Several museums are proud owners of major fakes and dont reveal it to the public because itd make them look stupid. One museum Im familiar with, The WInterthur Foundation and Museum has a huge collection of american decorative arts based upon the personal collection of Irenee Dupont. Apparently Mr Dupont was a favorite target of those who made fake pieces with the express purpose to decieve. Winterthur, instead of hiding their works under a basket, will do vast amounts of scholarship and lab analyses to determine just why the faked work was so good. They then have periodic shows about what theyve learned and these shows are fascinating .
I reacll a show that they did in 2003 about the fake peieces of American silver in their collections. They did extensive xray and metallurgical analyses to determine the material and makers methods between say, real Revere silver and fake Revere silver.
The results of their scholarship was a new high in conservatory sciences and forensics. I always look forward to their next show of "fakes and forgeries"
Just my two cent.