A rating system is unnecessary and might be used by troll armies to legitimize the illegitimate even so. What is necessary is what people like Jan Irving have already developed: https://www.gnosticmedia.com/links/brain/

Once you can demonstrate who pays for who it's not a question of "are they credible", but only of who to stay the hell away from, and anything else is a legitimization of the fifth branch of the government.