(1) People who write low quality posts are more likely to write again when they get negative attention. Furthermore, the quality of their posts deteriorates. This goes beyond the simple adage that you shouldn’t feed the trolls by giving them attention. The evidence suggests that negative feedback can perhaps actually create trolls. It also suggests that people getting negative feedback are more likely to give others negative feedback, too, spreading the infection.
(2) People who write high quality posts are encouraged by positive attention to write more. However, they aren’t as encouraged by positive attention as bad posters are by negative attention. Furthermore, the quality of their posts does not go up. Broadly speaking, encouragement doesn’t seem particularly effective.