What is the value of artwork? How do we determine? Why did it matter whether people knew or didn’t know whether these were original works?

“For his 13th day in New York, Banksy pulled a fantastic prank on unsuspecting passersby in Central Park yesterday by setting up an unannounced art stall with dozens of 100% original signed canvases. In a world where copies of unlicensed Banksy works are available for a dime a dozen, it’s not inconceivable for somebody to peddle cheap knockoffs for $60 apiece. To further camouflage the artwork the booth was labeled simply “SPRAY ART” and manned by an unsuspecting old man who seemed completely uninterested in what he was doing.”

http://www.thisiscolossal.com/2013/10/banksy-art-sale/

Similar to the case of Joshua Bell who played his violin at a busy train station and because no one knew who he was people didn’t pay any attention.