If a service puts me on a subscription list without asking me, and then at the unsubscription page throws a questionnaire at me as to why I am unsubscribing, I take that as dishonest behavior.

Obviously I am unsubscribing because I never subscribed in the first place!

Depending on how completely unrelated the subscription is to whatever I signed up for (say I signed up for online image hosting, and they start sending me emails about their fantastic paid backup service) then I mark it as spam even if the unsubscribe button is easy and single-click.

>Obviously I am unsubscribing because I never subscribed in the first place!

You never become uninterested in something after you subscribe?

Sure, that's another case entirely, and I wouldn't mark that as spam.

I was referring only to the cases where you sign up for X and you get newsletters and whatnot that's not really related to your use of X.

That interaction is not required, and therefore does not meet the stated criteria for spam-button retribution.

And for companies like MailChimp, it's a way to identify customers who are spamming people, and (hopefully) closing their accounts. If a high percentage of users are responding to the feedback form with "I never subscribed" then it's worthy of investigation.