If it is right that cookies only can be overwritten when cookies are set, we should see that the merchants get no clicks from us. The parasites are not able to generate essential traffic from themselves. They use our traffic to the merchants. So let's do the following:

We must dry the merchants out.

We take one merchant for special treatment and let him know that we boycott him unless he is parasites free.
If the above said is true, then the merchant must see a significant loss in traffic and sales. Then we take the next merchant. We here have the force to do that. Why should we not?