It causes their posts to be automatically marked [dead]. Users who have &#x27;showdead&#x27; turned on in their profile see these, but other users don&#x27;t.<p>[dead] comments that are good can be rescued if enough users vouch for them. To do that, click the &#x27;vouch&#x27; link at the top of the comment&#x27;s page (which you get to by clicking its timestamp). But please only do this for comments that are both civil and substantive.