One of the tactics the negative writers use is to mount a wave of attacks within a short period of time and then back off for a short time. And then come back again with higher intensity. The whole thing is psychological.
If they constantly attack, they will lose credibility. When they pause, people are psychologically relieved and their negative messages have time to sink in. Then, all of a sudden, "bang", they hit again. This is more powerful to get people follow their evil suggestions.
Give them "Thumbs" down and put them on "Ignore". Do not give them a reply and do not engage them no matter how upsetting you may be. This way, they do not receive bonus pay and you effectively narrow their forum to post more negative messages!