once you get paid via paypal- the money is real and guaranteed. That's one of the big perks of using it. Only way you could get 'scammed' that way is if the person then claimed you never sent the goods, or sent them the wrong goods. A simple signature required should eliminate that issue to a large degree, and even then, if he was a consistent scammer he'd get caught fairly quickly by paypal. If you really want to be safe, require money order payments, then you have zero risk of being scammed and only then the buyer would have risk of you scamming them (not implying anything here, just playing devils advocate.)
Once you get the money, the only way that the person could do something would be to tarnish your reputation on sites you frequent-but again, with the community judging your story vs their story should show who's telling the truth, as typically it's fairly obvious.
