Helping Merchants - Where do you draw the line?

I am a businessman and I want to ensure my long-term success. At times I will go beyond my responsibilities and provide free help in order to make an affiliate program better in the long-term. For example I have reported usability issues with order forms, tested the order process and helped design affiliate program websites to drive up the conversion rate.

I strongly feel that it is the affiliate program's responsibility to have a good website that will convert and track the targeted traffic I drive to it. The reason I provide this free help is because I know my commission check will grow as a result of a better user experience.

With so many affiliate programs and other revenue streams available, I have a hard time justifying this free help. I want to deal with professionals who can carry their weight. But often the best money is offered by good business people who are terrible web designers. Sometimes they are not even good business people but just have a monopoly on a very profitable product.

Where do you draw the line?