I have added the following notice to the donation page, as well some formatting changes to improve the appearance.
QuotePlease note: Donations and subscriptions are non-refundable. Donating or subscribing does not grant you special treatment, and/or exempt you or your posts from adherence to the terms of service.
I had someone donate $100, then posted 2 spam, which of course got their posts deleted and account banned by staff. The spammer then attempted to reverse the donation charges with Paypal by claiming they were fraudulent. Paypal upheld the charges, but I refunded their donation anyway; but I did not have to.
The addition to the donation page is to make quite clear up front that donations and subscriptions are final. That will be used with Paypal in the event of any future challenges.
Also Remember I have the IP Addresses used by you on my forums and Paypal can verify if those IP's have had authorized access to your Paypal account. If so you will lose a claim that the charges are unauthorized or fraudulent every single time.
This protects the site from false claims of fraudulent activity.