Has anyone complained about whether or not paypal is actually disputing chargebacks on our behalf or if they are just taking a fee from us? I wrote Am Ex after losing a chargeback dispute. Their response was unclear if my case was actually disputed, citing they did not have a merchant agreement with PayPal. I only found out the cc company because the buyer said she was going to file a chargeback with AmEx (since she was unable to file one through eBay since she damaged my item and returned it in a different condition) Of course, I lost the dispute through pay pal.
Source: http://www.paypalwarning.com/paypal-fight-chargebacks-fooled/