Though it may depend on what you are using Paypal to pay for, Paypal is a prime tool for scammers. You order, you pay, no delivery. You complain to Paypal, the scammer's account is empty and you get nothing. This happens at least once a week on a forum site I moderate. We have taken the only practical measures we can against scam sellers with 150 minimum post count and one year a member, iTrade rating, but in the end only advice we can give is either know your seller or use your credit card where you may get some protection if you report the incident quickly enough.

Any payment you make over the Internet you need to regard with the same care as you would to where you would leave your wallet laying around. Internet fraud runs in the billions according to something I saw recently.