Lately I saw several posts that were either badly formatted (did not use <p> tags for paragraphs just white spaces). It seems the preview feature is not really convincing. What else can I do to encourage people to format their posts better?

Duplicate posts: I also saw people posting the same message several times one after the other.
I guess the server did not give them a quick response so they realoaded the browser. In effect they created two post.
I am working now on a feature to hide a post but I would like to get ideas on how to solve this issue too.