Fortunately, counterfeit cash is not a big problem, says Hsiung. But when dealing with more than $100, he recommends getting paid online with a service like PayPal or with a cashier's check to avoid issues. Personal checks can be problematic because you don't know whether the account has funds, whether it's fake or whether the check was printed using a stolen identity, says Hsiung.
Cashier's checks, while easy to cash, do have potential fraud issues. They've gotten much easier to counterfeit in recent years, says Hsiung.
Also watch out for a common scam where buyers send personal or certified checks, often for more than the sale price, and ask you to wire back the difference, says LaPedis. In cases like these, the check is usually fake, but you won't discover this until later. "You'll lose the item and the money," he says, plus bank fees.
While this scam has been around for a while, it's still working, says Hsiung, especially with international "buyers." Craigslist warns on its website to deal only with local buyers you can meet in person, which will prevent 99 percent of scam attempts. The website also warns never to send funds via a wire service. Once you wire the money, it's gone.