I've had a number of attempted money order and/or bank cheque scams via CL. I always end the email exchange the same way:

them - "I can have my bank cut a cheque for my purchasing agent blah blah blah..."
me - "If your bank can write them a cheque, then they can also get cash. Have your agent show up with cash and I'll even drop the price by 10%."

I've never gotten a response after demanding cash, even when I offer to drop the price for a cash transaction.