There is currently no such thing as a "demerit". I'm hoping that the positive merits alone will be fine. I could add demerits pretty easily later on if necessary, though.
Maybe it's time for demerits to be implemented. I think that if a demerit subtracted merit from the sender too, or cost twice as much sMerit it would minimize abuse.
I think that is a terrible idea as it will just be used to demerit posts that people disagree with and as part of personal vendettas. I suggested an alternative that I don't think has these disadvantages. Do you have any comment on it?