If "--warnings" is used, only warnings of type "mac" are
issued.  The full potential of "groff" should be used, using
"--warnings=w".

  Lines, that remove warnings because of the use of old
"pod2man" (or other programme), should be removed when it has been fixed.

  THE PATCH HAS NOT BEEN TESTED:
--- manpages	2012-03-12 14:40:11.000000000 +0000
+++ manpages.new	2012-05-02 02:08:29.000000000 +0000
@@ -240,9 +240,9 @@
         # pages with .so but aren't simple links; rbash, for instance.)
         my $cmd;
         if ($path =~ m,^(.*)/(man\d/.*)$,) {
-            $cmd = "cd \Q$1\E && man --warnings -E UTF-8 -l \Q$2\E";
+            $cmd = "cd \Q$1\E && man --warnings=w -E UTF-8 -l \Q$2\E";
         } else {
-            $cmd = "man --warnings -E UTF-8 -l \Q$path\E";
+            $cmd = "man --warnings=w -E UTF-8 -l \Q$path\E";
         }
         my $pid = open MANERRS, '-|';
         if (not defined $pid) {
@@ -270,7 +270,10 @@
                 and (   $manfile[$1 - 1] =~ m,(?:https?|ftp)://.+,i
                      or $manfile[$1 - 1] =~ m,^\s*\.\s*UE\b,);
             # ignore common undefined macros from pod2man << Perl 5.10
+            # This and next line should be removed for wheezy
             next if /warning: (?:macro )?\`(Tr|IX)\' not defined/;
+            # This and next line should be removed for wheezy or its successor
+            next if /warning: (?:number register )?['`]F\' not defined/;
             chomp;
             s/^[^:]+://o;
             tag 'manpage-has-errors-from-man', $file, $_;

  System Information are for the 2.4.3+squeeze1 version (squeeze).

I strongly suspect that this would be grossly excessive in many cases;
the default is "mac" for a reason.  "man --warnings" is meant to be a
reasonable default for Lintian (I implemented it with that intent), and
it seems to me to be missing the point for Lintian to then override the
warning set to something else.

At most, additional categories should be emitted only at lower Lintian
tag severity levels.  But it's probably quite tricky to sort out the
different categories reliably in Lintian.