There are warehouses that specialize in nothing but returns and frequently have auctions where people buy pallets of goods for next to nothing. These buyers then resell on FB Marketplace and ebay. I've bought lots of tools off ebay from these sellers and everything has been perfect except for a battery powered hedge trimmer that included the battery, where the angle of the handle couldn't be adjusted. I messaged the seller and he sent a full refund and said, keep the tool and battery, which I was then disassembled and fixed.