Basically, never let anyone have access to your bank account. Also set up a seperate account for paypal transactions and only put in enough to cover any transactions in progress. Never keep money in your paypal account, clean it out and just keep what you need when you send funds.
Use a charge card to pay for any purchases (like ebay). Paypal, or EBay don't protect you, but VISA (etc) will go after fraudulent operators with a vengeance.
No agency will protect you...they just protect their own interests. Cover your own butt!!!!.