Don’t do that. Don’t sign up for your sponsor’s paysite through your own referral code, ever. Play with the join form. Go all the way to the checkout but don’t complete the transaction. Most sponsors consider this to be a violation of their Terms of Service. It’s cheating. If you tell them what you did, you take the chance they’ll kill your affiliate account. They may find out it was you and kill your account anyway. If there is a sponsor out there who will let an affiliate pay to join one of their sites in order to test things out, I haven’t heard of them. And for god’s sake don’t take this to the boards.

It’s understandable that you want to know whether or not your sponsor is shaving your sales. Sponsors have been known to shave or hide sales made by affiliates. Most of them don’t but that doesn’t discount the ones who do. I know a guy who pays his friends to sign up for his sponsor’s sites with their own credit cards. It’s a way I guess, but I wouldn’t do it.