Another trick scam artists on ebay have been using is to pay with Paypal an item bought and then cancel it.
The set-up being that someone has opened a legitimate Paypal account and attached a bank account and credit/debit card. All OK.
Then one day they go shopping on ebay for something nice - digital camera, mobile phone etc and use Paypal as a payment. Most Paypal accounts are set-up with direct bank funding automatically and the payment goes through as you receive the email stating payment has been received and so you send off the item.
Then after a day or so, they log-on to their on-line bank account and cancel the direct debit set up by Paypal, avoiding any charges rather than letting it bounce. Their Paypal account effectively then goes overdrawn for the payment amount once Paypal have received notification of the stopped direct debit. Not your problem you think? Wrong. After about 3 weeks Paypal take the money from you back and credit the scam artists' account back to zero. They then can close the account and reopen another one few days later with the same details.
Paypal do have some computerised automatic security check for this type of scam but for those who have built up a good buying reputation will be able to get round this. Bit like the gangsters' 'long firm' scam that's been around for years.