We received a very well put together invoice that explains how to pay their fake bill as well as future invoices. The letter includes their W-8BEN Tax withholding from and looks like you really owe them money. They even give you a nice color copy in back explaining how to read your future bills. Yes this should be caught by any well maintained AP department; however, these things jam up billing departments due to the approval processes required. Also, I'm sure many AP departments will let them slide through and some pay them.