I ask because Paypal does not guarantee intangibles like ebooks. However with domain names its unique because a transaction can be confirmed by looking at the whois info.
Paypal doesn't protect any online (website) transaction. Only tangible, physical goods are covered by the Buyer Protection Program that Paypal offer.
If you are doing a big transaction, don't use paypal. You should only use them for small amount transfers. For bigger transactions you can use escrow.