I'm selling a bike frame on Craigslist for $350. This guy Mark Dowell contacts me (mitsubishs@aol.com), says he'd like to buy it, and that he'll send me a certified check via overnight courier. The check will cover the $350 for the bike frame, as well as shipping costs. I'm to cash the check, then he'll arrange for a shipping agent to arrive and pick up the bike (as is). I'm to pay the agent with the excess funds Mark sends me.
All that sounded kind of okay. I wasn't sure why he didn't just pay the shipping agent himself, but I couldn't see how I could get screwed on the deal other than being charged too much for shipping. I asked Mark to verify that at the end of the whole thing he'd have the bike frame, and I'd have $350 in my pocket. He never replied to that.
The next day a regular check arrived by courier. Someone called "Bardy Cole" sent it (Bardy Cole, invo spline, 3435 East Thousand Oaks Boulevard, Thousand Oaks, CA 19362), and it was written from an account owned by "Sorkness Aviation Inc.". But instead of being for $350 + a normal amount for shipping, it was for $1,950! Wayyyyy too much.
Mark originally said he'd send me a certified check, but what actually came through was a regular check. According to answers in this forum, the check is fake, but looks good enough to be cashed. If I cashed it Mark would apologize for sending too much money and ask me to send the remainder back to him via Western Union. Later on my bank would realize the check was fake, take the entire $1,950 back from me, and charge me for the bounce fee. "You're out the amount of the cheque, the difference you send them, and whatever the property is, if you send it."
If you do a search for "craigslist fake check scams" you can find out a lot more. The FTC has a page filled with good information, and Craigslist has their own scams avoidance page.
I called the FTC (on 1-877-382-4357) and filed a thorough report with them. They told me I could now shred the check and ignore any further contact from the scammers. They seemed very familiar with the whole situation.