This is the kind of offer which nurtures and sustains scams. On the one hand, you have the seller selling something which obviously someone will buy not so he can send money to his grandma but for something far more sinister..
Then you have the buyer who (I'm sure) wants this account to receive money for bitcoins (or for craigslist frauds), fully aware of the reversibility risk and probably even exploiting that risk.
Trading these accounts might not be illegal but then again you have the fraud factor here. The account will almost always be used for fraudulent purposes.
Posts like this should be tagged with the brightest red possible.
Theres plenty of reasons people buy paypal accounts. Paypal limits accounts if people have to many charge backs. They limit accounts for too much volume. They limit accounts for all sorts of things. Lots of people dont know how to creat fresh paypal accounts. You need VCCS, Clean Ip addresses and some knowledge.
Theres an entire forum built for this kind for stuff called aspkin.com. Regarding fraud, thats paypals issue and they have there own system in place. I couldnt care less what people choose to do with the accounts. I will say its far more difficult than you imagine though. Many legitiamte paypal users get banned. Hence the need for people selling paypal accounts.