Yes it is possible to be scammed with paypal.I have been scammed once and paypal did nothing about it!
What usually happens is this, you open a dispute with paypal,the seller does not respond,you contact paypal customer services,and paypal will go on like since it is not an ebay purchase and was not purchased on an ebay site they can't do much about the transaction,and that you should try and work things out with the seller.
Your best option is making the payment with your card through paypal so if anything goes wrong you contact your card issuer and not paypal.Paypal is an ebay company.
Please note i'm only speaking from my personal experience.
Hope it helps.