“The art market has changed,” Coulson says. “It has gone from professionals only to a kind of luxury retailing where you have no idea who you are dealing with.” […] “For a seller, the worst is to be in doubt whether the work is actually sold or not,” says Jean Marc Decrop, a prominent dealer specializing in Asian contemporary art. Last year, Decrop found himself in that exact position, wondering if he’d ever see the money for a Chinese painting that went under the hammer in Hong Kong. (He finally did get paid, after four agonizing months.) Decrop notes that during the peak of the credit crunch, one U.S. buyer developed a cash-flow problem, but in that case—unlike with the Chinese purchaser—the American was open about it and arranged to pay via an installment plan.