Why does forged art lose admiration once the forgery is discovered?

…that most museums don’t want publicized: a TON of classical art, medieval art, and modern art is FAKE. I read a book once about the forging of classical art-there are workshops in Italy where you can have classical sculpture made to order-they bury the work in manure for a few months to age it, and bust it up a bit. The Renaissance era “world cup” (once attributed to Benvenuo Cellini) is most likely a fake-the thing is almost 5 centuies old, yets has no dings or scratches.
Buyers for many museums have been swindled in the past-of course now, we have ways to detect fakes…but imagine how Yale University must feel-they paid big bucks for the “Vinland map”-only to find that the thing is a 50’s era forgery.
There is even a strong suspicion that many of the later works of Willem DeKooning are fake-the guy was senile for the last 10 years of his life (his daughter is supected of painting them and passing them off has his).

Like this, supposedly:

www.marlaolmstead.com/gallery.html

The home page of her website is down, but her parents have posted a statement explaining their side of the story, which pretty much indicates they were set up to look bad either intentionally or because of time and money constraints, by 60 Minutes, and that they will soon be posting video of Marla painting start to finish.

While it’s long been my belief that 60 Minutes decides the outcome of its stories before it ever sends out its reporters, I still have a hard time believing this little girl did all these paintings all by herself. Nonetheless, the painting she did eventually produce for the camera, though not up to par with the rest of her supposed work, was still good enough to lend a certain amount of credibility to the possibility that work is genuinely hers.

So in other words, I don’t know who to believe.

The statement by her parents regarding the 60 Minutes segment can be found here:

http://www.marlaolmstead.com/