Technically this scam doesn't revolve solely around picture frames but a recent victim reported that he was a victim of the scam and he was selling his old antique picture frame. This scam is for all purposes a "bait and switch" scam that can happen anywhere but the scammers seem to be targeting users of Craigslist that live in San Diego or at least advertising on San Diego Craigslist.
They will normally target victims who are trying to sell something that is hard to sell and have been listed on Craigslist for some time. This means that the seller is getting desperate and is more likely to follow through with the scammers instructions. The price or the type of product being sold doesn't matter. What matters is the transactions that the seller is willing to do.
The scammer will almost always pose as a person that is not in town and will be in town for a short while sometime in the future. Because of their time constraints they have to complete the transaction before they reach town. More than likely, they will be from Africa. Sometimes the scammer will call you but they will almost always contact your through email to show their "interest".
They will feed you a story and try to construct their way to make you believe them and their "unique" situation. The item, the delivery details etc aren't important. What is important is that the scammer will always insist that they need to pay by credit card, normally Visa or MasterCard.
The card details that they offer the victim will be real. The money will be transferred and it will show in your account. The glitch will be that the scammer will say that they have unfortunately given you too much money by mistake and ask that you wire the money back to them. They will insist that you use Western Union. Western Union is great for scammers because once the money is picked up from the other end it is impossible for the money to be traced and recovered.
The victim will normally not see any problem with this as they already have the money in their account. Correcting the mistake won't seem to pose any issues so most victims will happily comply. The only issue is that this is where the scam happens. After the scammer has received his "extra money" from you, he will perform a "Charge-back" from his credit card. Most charge-backs are successful and if you haven't taken the money out from your account, most western banks will comply and deduct the money out of you account.
Ultimately, the scammer will get his money back plus the extra that you have sent to him over Western Union. Your item will most probably be lost because of the bogus shipping address that was provided. This scam really screws with legitimate sellers so those in the San Diego area should be particularly careful of whats going on. Some tell-tale signs will be the buyer coming from Africa, wanting to buy an item unseen and also insisting on using credit cards only.