Half the time, clicking the unsubscribe button leads you to another form that is almost impossible to comprehend, which results in (maybe) unsubscribing you from one list, but subscribing you to fourteen other newsletters and update and special offer lists, for a net increase in spam.
If the email says "click here to unsubscribe", then it should do exactly what it says. Taking you to a page that allows you subsequently unsubscribe is not sufficient.
And yes, you should only ever follow links for companies that you are confident are not spamming you out of the blue, because of the danger that you are just confirming your email address is active.
My other gripe is that I'm not sure how anyone is going to tell that I have clicked on a word in an email, given that it's displayed on an xterm. But if they say that by clicking on it I am unsubscribed, it's their problem to make sure it happens.
