There have been a lot of good points made already in this thread...both Zebra and sykkboy have hit the nauil on the head.
Speaking from personal experince, with Python running naughtymail, I can tell you that we get spam AND spam cop complaints from people that have opt'd-inthrough the double opt in process.
With a list as large as our we queue up mailers 3 days in advance and people that have opted out still get mailer from us for a few days. This is stated in very explicit terms during the opy-out process...but we get complaints anyway...and I love that spamcop has the tendency to mutiply ( exponentially I think sometimes) the number of complaints they send out.
I run the Dollar Machine affiliate program for Python take a LOT of double opt in mailer traffic, quite a bit of it from people who post here and i know that they legitimately collect their e-mails through a double opt-in process...but still get up to 10 spam cop complaints a day when they mail the list to my sites.
Do I treat them as spammers?....Hell no.
As Zebra mentioned the line between spam, single, double and triple opt-in e-mails gets very blurry as defined by the people receining the mail.
In the end it boils down to a trust issue for me.
And from what i have seen based on our mailing operations ( double opt-in) there has been no decrease in profitability....but we have had to constantly allow our business model to change with what our clients and the people receiving our mailings want.
