QuickRewards is doing their payments through PayPal's Mass Payment, which they pay a small 2% fee to send. Payments sent through Mass Pay do not have fees for the receiver. Mass Payments can only be sent from existing PayPal balances, not payments from a bank account or a credit card. Also, if a payment is sent using the person's account balance the regular way (not a mass payment), the receiver would also have a fee. Those would have to be sent individually, which would result in the receiver having fees.

If you are sending money (or receiving money) from someone that you know, the "Personal" payment tab can be used, which won't result in a fee for the sender or receiver.

Unfortunately, it's hard to tell which sites use the mass payment option until you actually get a payment from them. Payments from site's can be sent as a personal payment since there isn't a personal relationship between you and the site. Some sites don't mind paying the 2% fee, others prefer to just send it the regular way and have the receiver deal with the fees.