Legitimate emails with Unsubscribe links are really only 'supposed' to come from those you have given permission to contact you or previously interacted with. When I encounter one of these I don't hesitate to use the Unsubscribe link and I find it works. For everything else I hit the Spam button that Gmail thoughtfully provides, and that works too.
I also do use a couple of filters to automatically throw some things in the Trash. I do this when I get emails from a board I have signed up for but where I don't want to see posts from a specific person because I find they post too often or post nothing I find interesting.
Dave