Thought:
Thus, I reckon we should have one more counter (similar to merit & trust), that would basically count "obnoxiousness level".
Giving someone an "obnoxiousness" would be like claiming this user is bad, this user is constantly rude, this user swears etc.
1. This meter would be a simple negative decimal number. Could also be positive, but I believe a negative number would better indicate the "meaning" of the counter - which is showing how bad this user is.
Considering the level of personal enmity and grudges we see people have with each other, what makes you think such a system wouldn't be used unfairly by such people to make each other look bad in the eyes of the general public of this forum?
User A giving obnoxiousness to User B will give a negative obnoxiousness number to User B, but what if User B is not a rude or bad person in general but User A has some personal problems with them? A person doesn't have to be called rude or bad only if they have problems with one or a few people that they had some argument or fight with in the past. If you are giving another user obnoxiousness makes them have a negative value, the person might not be a bad person to me but now he would look like one to anyone who sees their profile.
Even if you propose that there should also be a way for people to give them positive points to reduce their negative obnoxiousness level, it will still not stop the unfair usage of the system, in my opinion.