I noted something rather annoying (or maybe it's from specs, but I find it deceiving). I made a question having the tags linux, windows and osx (because the question specifically asks for all three of them).
In my tag filtering, I am interested in linux but I exclude windows. The end result was that my question was hidden (transparent, and I guess completely hidden if configured it as such), but at the same time highlighted in orange.
In my opinion, this is a bug. If something contains a tag I am interested to, it should overrule the fact that it also contains tags I am not interested to. If I want to address a broad audience (which would be the reason why tag it linux, windows, osx) putting all the three tags is a guarantee for having the question receiving only those readers who don't have any of them in their exclude list (not many, I guess)