I'm looking for a URL hack of some sort to enable me to exclude posts that have a value assigned through a custom taxonomy. I have items I'm importing into MailChimp via RSS and want to exclude items that are marked as featured through a custom taxonomy. I'm using Custom Post Type UI to manage things if that might factor in at all.
For example I want to show everything except what is marked as featured in my RSS feed.
I know I've done it for categories before, but I'm coming up empty when it comes to what I need to do. I noticed that all the categories, tags and taxonomies all share the same number space for their ID values, but for some reason the URL queries won't work when I try just using the category features.