My rule: If there isn't a prominent, 1-click unsubscribe link in an email, it gets marked as spam.

If I click unsubscribe, and the form asks me to fill in information, it gets marked as spam. No, I'm not filling in my email, let alone completing a CAPTCHA, to ask you to stop sending me emails.

However, I don't click an unsubscribe link in an email where I suspect the unsubscribe link is itself a scam to collect information.