You are welcome to take a look at "How it works" section at Foxico https://foxico.io/howitworks
Logic is explained. In few words I can describe it here:
Behind each rating stands a weight (that is acquired by quality of this person's ratings) that influences the final score.
Anyone who rates can be simply liked/disliked by others members and it influences the weight of this particular expert. Therefore the final score of an expert who got a lot of dislikes does not influence the total score of a project and his scoring has low weight as a result.
For example when you see someone rated a scam with a 10 you simply dislike it just as others 10 people do and this person (who rated) loses weight immediately and later his score doesn’t influence the total final score.
Math stands behind the system that leads to fair ratings.