Although I don't send spam, I do collect double opt-in e-mails from my own sites. With the software that I wrote, I collect things from the user when they single & double optin, like IP, timestamps, user-agent etc. This way if someone needs proof they have it. I typically use these e-mails for a 2nd attempt to get them to join my sites since I collected them from the site in the first place. I do not send e-mails and if someone asks to be removed...they are simply removed.
I do however know people who do this full time and make good money off of it. (Neighborhood of 200-300 signups day.) One actually furnished his house with things he received from affiliates he promoted. I think the thing that bothers me the most, is that most affiliate programs say they are against spam, but send it anyway or even hire people to send it for them, or turn a blind eye to it.
I also think e-mails can still be profitable if used properly. In many instances cheaters will use tools to pull e-mails off of message boards and other areas and use those instead of double-optin methods. I think most of it is that users are just getting smarter. Just as the "pros" like to signup for trials, then cancel, then signup again, then cancel. These people know how to get free porn, so they run around all the sites to get free porn in their e-mail and they do it to their hotmail accounts so wife-poo doesnt find out.
An now for Jerry Springers final thoughts
I think that if you run your optin campaign like some due (including me) where you are open and upfront with the people you send mail to about how to be removed from the list and you send it to people who double opted into your list, and treat them with respect, and don't send 3 e-mails a day for 3 months, you will have people respect that. I think anymore anyone who enters their e-mail address expects to get "spam", its how you deal with it that makes it better imho. The people who brutalize my inbox with e-mail I never requested 30 times a day with "I got a secret website" messages...should just be shot. And the bad thing about adult webmaster spam, is that most of these guys that do it, if you try to remove yourself, your e-mail doubles because now they know they have a keeper.
These are just my thoughts though.
Andy