I have not really ever put together an organized optin mailing program so I can't comment about that.
What I do know is when I signup myself for certain things to see what they are about and then regret that I did because it never opt's you out of their program even their fake opt out page, etc.
I have made it a habit as well to use alias e-mails for certain sites so I can see how they sell and resell my information to others as well.
I might sign up for x site, so I will use x as my
username@mywebsite.com that helps me in tracking since I don't allow any e-mail to bounce.
I have been caught up on the never ending opt out on naughtymail like forever, so if anyone knows any tricks with them please let me know. lol.