This one doesn't just catch tourists: Tricks and scams that manipulate the exchange rate -- the value ratio between two nations' currencies -- can even catch savvy government officials. The United Nations revealed in 2008 that it lost millions of dollars in aid to Burma after officials in that country manipulated the exchange rate to swindle the international aid agency during an aid donation [source: Buncombe].
Many developed countries have national regulations on who can exchange currencies, and their exchange rates are typically set on a nationwide level. Travelers can trust that the rate won't fluctuate between two banks on the same street, although some countries may allow moneychangers to charge varying service fees.
In less regulated countries, however, the money exchange game can be tricky -- and costly -- to play. Anyone with access to a little cash could set up an exchange booth, charging whatever array of fees -- and manipulating the exchange rate -- as they see fit.
The best way to avoid the expense of an unfair exchange rate is to exchange your money before reaching an unregulated destination. You will need to carry the money in a secure fashion as you travel, but you'll know that you didn't pay more than necessary to switch to the local currency [score: Scambusters].