Anyone can change their posting habits if they are committed to doing so. The only limitation is that most spammers have account farms operating multiple profiles at the same time, which makes it difficult to churn out quality content.

Limiting the accounts you post on and putting some effort into the conversations you join on the forum is a sure step to making anyone's posts constructive. After a while, the user can send a message to who left the feedback asking them to review their post history.