Yes, the scammers send a fake check. I had one send me a check for $18,000. They send a check for more then the amount you are asking and ask you to Western Union the difference. The difference, of course, comes from your real bank account, you send it, then their check bounces. It sounds really easy to trace and arrest someone, except in Nigeria, where most of these are based, there is no legal system enforcing this. I am an I.T. pro, and traced the IP address of the sender to Nigeria. The Secret Service (they oversee forged instruments, including checks) said there is nothing anyone can do about it. (I of course knew it was a scam, but I played along to see the fake check, and it was an e-mail address not tied to any personal info).
It takes a big man to cry...It takes an even bigger man to laugh at that man.