If you go directly to the store or do a google search and come across the store, they will record your visit on their end. If you browse their site and then come to our site and click on our link before making the purchase, they reserve the right either to not pay me at all or to pay me only a minimum amount.

Their justification (which in part is true) is that you found them without me and would probably have made the purchase even if they were not on my site. So why do they owe me any money for the purchase?

Of course, we argue that you might have decided NOT to make the purchase if you did not get cash back or that you maybe bought MORE because you were getting cash back or I gave you a good coupon. But that's only rhetorical and we can't prove it.