I wonder how much they are duped.
It's not that hard for them to find a dupe. They blast out messages through email and Yahoo chat all the time from textile companies looking for "agents" in the US. They usually have some excuse about how they got your contact info. They blast out enough so the hit ratio can be minuscule. Not everyone is savvy about things related to technology. Most who fall for it are probably idiots, but even people who are intelligent in other things have fallen for it.
The scam goes something like this: You're dupeA, they need an agent in the US to process payments, because the tax law is such that it makes the business taxes they have to pay significantly less than if the payments were processed offshore. Sometimes they do indicate that their avoidance of taxes is a gray area, which discourages people from talking about it with their friends who might tell them what's up. It is your job to simply print the checks (dupeB sent you the blanks) and mail them in the amounts and destination they tell you. In exchange, you get a commission, which essentially means writing yourself a check and depositing it into your bank. DupeB's job was to order the checks online, supposedly because they can only be sent to a US address, and DupeB is given a real bank account number to have put on the checks. DupeC is who gets the check you sent them. DupeC is selling something on craigslist, and the Nigerians have contacted him saying they want to buy his item and they'll arrange for their shipping agent to ship it to them, but the only way they can send DupeC money is by having their client, who already owes them money, send them a check. However, the amount the client owes them is more than the sale price of the craigslist item. So, DupeC needs to go deposit the check from the client (actually DupeA) in his bank, then send the difference to Nigeria via Western Union, minus a little extra for the inconvenience.
And of course, once the checks fail to clear, your bank takes back the amount of the check from your account, and DupeC is screwed out of whatever amount he sent via Western Union.