And this is why I never subscribe to newsletters in the first place.

Getting two new spams because the company you unsubbed from sold your address

or just use one email for registering to forums sites etc that are just for killing time, and use diff email for making online purchases paying bills etc

Confirmation emails prove nothing. There are recruiter backalleys that nevertheless continue to spam emails, after "confirming" unsubscription.

Don't ever click unsubscribe if you didn't actually subscribe there in the first place. The only thing you are doing is showing spammers that someone is actually reading it at the other end and that it wasn't filtered.