When displaying the questions on a site, questions with a Favorite tag are highlighted, while questions with an Ignored tag are grayed out. Questions with both a Favorite and Ignored tag are grayed out, which I think is good. Ignored overrides Favorite. I can Favorite "audio" on Stack Overflow, but then Ignore "iphone audio" or "jquery audio", which I have no interest in.
We now have a "Favorite Tags" feed, which is great, but it doesn't pay attention to the "Ignored Tags". I think Ignored tags should override Favorites tags here, too, and not show up in the feed. It should behave the same way as the site.
If there's a legitimate reason for Favorite to override Ignored, then both options should be available.