You're right, user B could make incorrect (to me) ratings about other users.
Similar to what you say about derived and produced information, I would have "personal" and "external" ratings. My personal rating for user C (that I make after reading some of their posts) would override all my other external contacts ratings of user C.
Over time, if I have a high percentage of different personal ratings from user B's ratings, then the system would apply less weight to his ratings for other users.
Similar to what you say about derived and produced information, I would have "personal" and "external" ratings. My personal rating for user C (that I make after reading some of their posts) would override all my other external contacts ratings of user C.
Over time, if I have a high percentage of different personal ratings from user B's ratings, then the system would apply less weight to his ratings for other users.