internet scams how to avoid??

Your correct Lawrence, it's a scam. The older versions entailed you getting a check for your sale, but over the sale price, where you "send them back the difference."

Safeguard: I've seem some guys make you reply back to the Ad with certain keywords in the subject line, to verify your human.

I was selling a car a couple years back on CL, got a text with someone "interested." I could tell straight away it was a scam, and messed with the person a bit. I told them to come on down and check out the car, that they needed to drive it first as all 4 wheels tend to fall off the car going down the road. They replied that that didn't concern them and that they wanted to send me a check.