Wouldn't a rumor of counterfeit have the opposite effect -- of creating an expectation of contracting supply for real dollars and a desire to hold onto the real dollars instead of use them since if the rumor were true it would mean that every dollar held contained the change that it would be unusable in an actual transaction?  It's the threat of counterfeit that would drive people away from using dollars as money, not that gold in of itself would be more preferred than dollars. The same could be said of gold if an effort to counterfeit gold or, lower the weight of gold coins, were also to occur, something which is easier to do than counterfeiting dollars. The issue isn't that you're wrong but that the Iranian case doesn't seem to have the elements necessary to back up your point.