Can someone ask for a chargeback for his donation via paypal ? If he/she can't ask for a chargeback, it is a best way to fight against scammers . It will help to protect the services providers/sellers .
You can chargeback even if it is a donation. I was reading about it here: http://alexking.org/blog/2009/03/23/beware-of-paypal-donation-chargebacks