THE ABSOLUTE BEST WAY TO PREVENT A SCAM LIKE THIS -
Have the buyer send you an email from their paypal email to your paypal email. This will at least build confidence in the transaction, because it's more likely to be their account.
Also, have them call you from their phone and see if the phone numbers match up with the name. Regardless, if the guy files a claim you can tell paypal you spoke with him on the phone. If the phone number matches up with the guy's address you will win the case hands down.
Remember, when I say show paypal I don't mean speak with a paypal rep. I mean speak with a supervisor or the resolution team YOURSELF. This means you keep nagging the paypal rep until they hand you over to the senior rep, who then needs to hand you over to the resolution team.