You can highlight some good comments and feature them and that helps in encouraging your site visitors to comment and take part in ongoing discussions and at the same time it also enables you to discourage unwanted and useless comments, the comments which are not giving any value addition. This tutorial is on a cool WordPress plugin called Featured Comments, the plugin enables you to add “featured” or “buried” CSS class to some selected comments and you can very easily highlight comments which are adding some value to your blog post.
So to set up this new plugin, first install and activate Featured Comments plugin. Upon activation visit Dashboard -> Comments page and you will be noticing new ‘Feature and Bury’ links after each comment. And after you feature a comment, it will turn green in the admin screen where as buried comments will go dimmed. You can do same thing (feature/bury comment) from single comment edit screen also.