Well I have used Paypal for over 5 years buying and selling. I have to say if you follow thier guidelines you will never have a issue. First off when you send someone a part, always charge for and get signiture comfirmation. The person usually has to go into the post office and sign and show ID. When and if you send something bought with Paypal use their shipping method, and printing which takes the money right out of your account and keeps all the tracking info, and also 9 times out of 10 is cheaper. Its hard to dispute something they sign for and show ID and Paypal with always side with you. The only time it is a problem, is when someone puts a claim about the use of their credit card. That is when your seller protection kicks in and Paypal will chase the money, you are in the clear. I am sure there is a rare occassion this doesn't work, but I will give you a excellent example. Goody took a non deposit on his car and I think the buyer was trying to pull a scam, she wanted the car delivered before we got payment, blah blah and we followed all the rules. She put a claim into Paypal for refund of the deposit and paypal sided with us, and we kept the deposit, so personally I only do business with people who use paypal on ebay and it has worked fine for us. Lastly, even though the account is in negative, read the small print, Paypal will go after your credit report and personally I keep my credit excellent so think twice before you dont feel like paying them, I know you know they are aware of the no balance in your account plan, your are not the first to do that so think about it.
-JR