Originally Posted by signupdamnit

Because it's like stealing. Your affiliates aren't sending you traffic so that you can make money on other ventures or sell that traffic to others. They are sending you the traffic with good faith that you will honestly try to convert it in a direct manner. If you want to do stuff like this then start paying your affiliates per impression or per unique.

At the very least the ethical thing to do is to send out a mailer admitting that you are doing this. Suddenly sneaking it in there without notice is crap and is part of the reason why many affiliates are leaving the industry. Even if it hurts affiliate conversions by 5% that can be significant. It's also the principle of the matter. If you do this what else are you doing? What's next? It's like catching a thief.