To date in well over a decade of using Paypal I have never had an echeque bounce although I have had the odd one that has taken an extra couple of days to clear. If it happens I would first contact the buyer as there have been posts claiming that Paypal have cancelled payments when there has been no reason, I don't give it any more credence than the cat bid, not me but I would give the buyer the chance to re make the payment before proceeding like any other unpaid item case.