This is a very good point. It's funny because someone who I have promoted for in the past sent me a message on Skype the other day and asked why I just unsubscribed from his JV partner list. I told him that I didn't know because I usually don't unsubscribe from the JV lists...
I went back through the last e-mail he sent me... He was using his JV list to do adswaps.
That's an instant unsubscribe for me if I'm a JV and you're using that list for swaps.
Matt