From my experience with Skrill, its rather hard to get charged back or to charge someone back. I got scammed a while back and attempted to chargeback the scammer. Upon calling Skrill, they told me that since the payment was from one personal account to another (meaning I didnt send payment to an official website/business), I would have to call my credit card company. That didnt yield much either, since in order to send a payment via Skrill, you have to verify yourself with some rather specific information, like birth date and CSV code.
In short, my experience with Skrill is that chargebacks are rare.