If I do a search for Ruby questions without answers, questions with tags I ignore are not shaded out. For example, doing [ruby] answers:0 shows Stripe remember me everywhere not displaying un-shaded, even though "ruby-on-rails" is an ignored tag.
I assume the rationale for not ignoring questions when you're doing a search is that you're searching for content, and you don't want to hide content. But if you've got answers:0 in your search, it's very likely that you're searching for questions, not searching for content.
I've heard of other ways to search for questions with no answers, or no upvoted answers. There's the "unanswered" tab for a tag. But that sorts by question votes, not by how new the question is, or how active the question is. There's also https://stackoverflow.com/unanswered/tagged?tab=mytags , but that seems to sort by question votes, not by newness.
