The default comment moderation system in Drupal 6 is crude at best primarily because of the limitation of the admin comment listings. The information that is shown by default are 'Subject', 'Author', 'Posted in', 'Time' and 'Operations'. Now the main objective of comment moderation is to reject spam comments. None of these fields give any information about whether the comment is a spam comment or not and you will have to view each comment by going to the edit view of the comment and then approve or reject the comment. This is a very laborious and frustrating process. You have three options to solve this problem and get a better comment administration interface - one is to create a comment view, another is to alter the default comment administration form and the third is of course a custom solution for comment administration.