If you sell goods online, you'll want to keep an eye out for suspicious activity coming from a scammer who claims to be PayPal. Here's how it works: An "interested buyer" will contact you and ask you to accept payment through PayPal. You'll then receive an email that looks like it's from PayPal, saying you've received payment. If you check your PayPal account, the money isn't there. Unfortunately, many people don't take the time to check...