Just tried to unsubscribe from some InfoWorld email newsletters at the unsubscribe page. Go check it out. I'll wait.
I got to the page by clicking a link in an email they sent me, meaning they already had my email address. Of course, when I got to the page, they hadn't filled in my email address. Or actually checked what I subscribed to. Instead, I get a text box to enter my email address then 41 check boxes that I can select to unsubscribe from that individual newsletter. No way to select all of them, or even groups. No hint as to what I actually subscribe to.
So, guess how I determined there are 41 check boxes checked? I counted each one as I checked it to unsubscribe from every InfoWorld newsletter.