Not false or true, but it would already help to check if the text is an opinion piece. Lingustic hints for that should be relatively clear, as opposed to for ex

Not false or true, but it would already help to check if the text is an opinion piece. Lingustic hints for that should be relatively clear, as opposed to for example encyclopaedic style. That way they could both exclude most Breitbart stuff as well as editorials from actual newspapers, which shouldn't make it into quick-info fact boxes either.