From my experience, the straightforward trade where a subscription to the band’s newsletter (or reactivation if you’ve previously unsubscribed) is the price for the free song is the scenario. Right or wrong, people mark those newsletters as spam or delete them without opening them to check for an unsubscribe link.

People will mark spam as spam, but they also have no hesitation about marking legitimate bulk e-mail they willingly signed up for but are no longer interested in as spam as well.