Wandering around any foreign city (domestic or otherwise) lowers your guard and increases your profile making you susceptible to scams. The Time Online lists 13 elaborate and unorthodox scams to beware of.
You??re tired, there??s a queue at the taxi rank, so you accept the cheery offer of an unofficial taxi. From this point on, a good outcome is that you??ll be overcharged, or forced to stop off at the driver??s brother??s souvenir shop on the way to your hotel.
Many of the tricks seemed to be based out of South America but even the savvy traveler can get caught off guard anywhere. A good piece of advice is never to accept money (or drugs) since you can be put in the place of a crook. Also only ever trust the travelers you know, many of the scam artists tend to enlist locals with backpacks to make you feel safer.