Wysiwyg Comments is not turning off
For Drupal 6, I normally add the following to a custom module:

function mymodule_form_alter (&amp;$form, &amp;$form_state, $form_id)
{
  if ($form['#id'] == 'comment-form') {
    $form['comment_filter']['format'] = array(); // nuke wysiwyg from comments
  }
}


To be honest, I can't recall why I am using $form['#id'] instead of $form_id for the conditional.