People looking to sell a used couch, electronics, or even a used car look to online classifieds. They’re easy to use and give sellers the opportunity to connect with lots of potential buyers.
However, scammers impersonating potential buyers troll these sites looking for victims they can scam. The scammer tells the seller via email they have added courier/transportation costs in the payment they have made online to the seller and the payment will not be released until the seller sends the money back using a money transfer company. The seller sends back the money as requested and the scammer never releases the payment so the seller is out the money that they sent.
Roles can also be reversed where the scammer preys on buyers who bid on items using an online auction website or service. The buyer sends the money for the item, but after the money is sent the buyer never receives the purchase.