In http://forums.b2evolution.net/viewtopic.php?t=5820 ega1 came up with a way to show the commenter which word in their comment matched the antispam list instead of just saying "not allowed". This hack adds to that a bit by saying that a commenter who happens to be logged in will not have their comment compared to the antispam list.

In htsrv/comment_post.php find around line 87 something that looks like this, then make it be this:

if( empty($comment) )
{ // comment should not be empty!
	errors_add( T_('Please do not send empty comment') );
}
elseif( ! is_logged_in() )
	if( antispam_check( strip_tags($comment) ) )
	{
		errors_add( T_('Supplied comment includes a disallowed term: <strong>'.$block.'</strong>' ) );
	}