Appealing as this idea may be, I think it is wrong. Good faith attempts at objectivity in journalism are a relatively new feature — appearing maybe half way through the history of the printed word, or even later? Isn’t it so that in the early US, all papers were wildly and openly partisan? I think a better service would be to identify sites as proudly partisan or attempting to be objective. Maybe a five point scale: proudly far left, kinda left, attempting balance, kinda right, proudly far right. There is real value in such explicit context.