A good Samaritan is a person who goes out of his or her way to assist a fellow human being. When you're traveling in an unfamiliar country, you might hope for a good Samaritan to help you find your way. Unfortunately, however, some "good Samaritans" are actually con artists in disguise.
Some people will offer to "help" you use an ATM. Beware -- they're only trying to get your PIN code. Or, some thieves set a "trap" in the ATM that will cause it to eat your card. Ensure there is nothing sticking out of the card slot at any ATM before you use it. There could be a mechanism to steal your card.
Others will hang around at train stations and ask if you need assistance purchasing a ticket -- then take your money and run. You should also be wary of people at train stations who offer to show you to your seat. When you get there, they will demand payment.
While driving, a car may pull up next to you and the driver will helpfully point out that you have a flat tire. While one person assists you in changing the tire, an accomplice will help himself to your pocketbook or any other valuables. Oftentimes, the people that flag you down are the people that punctured your tire to begin with.
In Spain, there's a popular scam where an older woman offers you a sprig of rosemary, as a sign of friendship. Then she'll grab your hand, read your fortune and demand payment.
How do you avoid falling victim? Don't make eye contact or accept anything that's handed to you. Purchase any tickets yourself. If you need assistance, utilize the concierge at a hotel. Never let anyone help you out at an ATM, and never give anyone your PIN.