The victims usually deposit the check. The buyer then directs the victims to pay over the extra cash to the company that picks up the item. The victim sees that the cash is in their account and thinks everything is okay and sends the cash. Later the victim will have their bank reverse the deposit and probably be contacted for presenting a fraudulent check.
I contacting the poor guy whose account was getting drawn on and he said that there were over 35 checks in the $1800 range presented for payment to his account in a matter of three days. Needless to say he said it was a nightmare.
I think the advice is to deal with locals only.
The above thread is a scam on Craigs list, not ebay.
This happened to friends of mine, selling a car. They didn't ask me about it until AFTER they lost $3,000.