A decentralized anonymous exchange...
"Bitcoin is an experimental new digital currency that enables instant payments to anyone, anywhere in the world. Bitcoin uses peer-to-peer technology to operate with no central authority: managing transactions and issuing money are carried out collectively by the network."
Bitcoins are Bitcoins. You can be sure they're not hacked, faked, covered with drugs, linked to a criminal, etc. One Bitcoin is exactly the same as the next. Buy with confidence
Although, I'd really recommend leaving Paypal out of this. Moneypak would be a much better way to go, and this guy that you're trading with doesn't seem right.