Ironically, in Cambodia they DEMAND crisp, new USD. Ironically, its more likely for a crisp bill to be counterfeit. However, for whatever reason Cambodians will ONLY accept USD (from foreigners, anyways) that is completely minty fresh. I tried to pay for a Angkor Wat ticket with a $10 that was slightly wrinkled and the lady stonewalled me until I was able to fish out a brand new one. What a joke.