I suppose you could read the PayPal policy and find out what it says.

Yes, there are scammers on eBay who take the money and then don't send the item. If you put in an item not received claim with PayPal, they will refund your money, unless the seller can prove they have posted it (by providing a tracking number). If the sellers PayPal account has been emptied out, PayPal will go after them for the money.

A seller can't just ride off into the sunset. Their account has to remian completely inactive for 60 days before they can close their account. On the other hand, eBay can close their account when they feel like it if the seller has been breaking the rules.