Most contracts with merchant bank providers specify 1% of total volume as a "reasonable" number of chargebacks! Although some individual banks set the line in different places -- mostly due to the fact that the credit card companies impose heavy fines on them if they don't drop merchants who incur a lot of chargebacks. (This is the major reason why most adult-services providers will very, very clearly explain what the charge will look like on the credit card statement, and why they are so careful to keep their charges looking inocuous. So, charges don't come from "BestialityPornUnlimited.com" on the statement, it'd be from something like "BPU Enterprises". Stuff like that. It's to eliminate the 'shame chargeback'.)

(It's also why most merchants, us included, make it so clear that if people are unhappy with services they've purchased, they should just ask us and we'll do whatever it takes to make them happy. I mean, over and above just wanting to provide good customer service. The chargeback is sort of the tactical nuke of the credit-card processing world.)

And I never mind questions. :) It gives me an opportunity to wax tl;dr at people! (What can I say, it's a weakness.)