Originally when PayPal started I think they did have a guarantee on all transactions. However, it appears that is not the case now reading their complaint policy as currently posted.
https://www.paypal.com/cgi-bin/websc...plaint-outside
Regardless, an alternative is also to use an escrow service. They HOLD the payment for merchandise for the seller until the buyer receives the merchandise. Once they have then the escrow service releases the funds to the seller. Otherwise, the funds are returned. I've used this type of service before myself.