A co-worker of mine got scammed on Facebook when she clicked on one of these ads. She thought she was buying a set of T-fal pans from Walmart.
She lost her money, never received any pans and a few weeks later her bank account was drained and identity stolen. It took her several months and a lot of work to get the bank to give her money back.
My boss's husband clicked an ad on Facebook to buy a too good to be true $19.99 hammock. He actually got something from the company months later (slow boat from China)....only it was a Barbie doll sized hammock and came in a small envelope. She is always trying to keep him off of Facebook. He won't listen. He's in his 80s and unfortunately very gullible.