have a quick read of the paypal regs mate.
folk like the payment owed since it can get them out of paypal taking a cut but i have noticed that they are starting to.
stick to sending money for goods or services and fill out in the added details part what you are buying, for how much from whom and from where.
also remember paypal only cares about disputes made over a payment in the last 30 days. if you have an issue after that paypal couldnt give a monkey !!!