.. it still doesn't answer the question as to why the "preprocess" glob of *.pl *.txt in my earlier snippet returns the directory name

Actually it doesn't. Your "wanted" function prints it when it is called with the directory name before "preprocess" is called with the directory contents. The first thing I did with your code was to add 'print "GLOBBING\n";' to the preprocess function. The directory name is printed before GLOBBING.

Sounds like you want to change the $filespec regex to only exclude directories you don't wish to traverse. Then filter out the rest of the directories in the "wanted" function. You could create a list of directories as keys to a hash and have "preprocess" skip any directories in the list.

Update: Added code

#!/usr/bin/perl -w

use strict;
use Cwd;
use File::Find;

my $filespec   =  qr/\.(?:txt|pl)$/;
my %dirskip = ( 'path/to/dir' => 1,
                'path/to/another/dir' => 1 );
                
my $dir        =  $ARGV[0] || getcwd(); 

find( { wanted => \&find_function, preprocess => \&globber }, $dir );

sub find_function {
  return if $File::Find::name !~ /$filespec/ || (-d $File::Find::name)
+;
  print $File::Find::name.$/;
}

sub globber{
  my @files;
  foreach(@_){
     push(@files, $_) unless $dirskip{$File::Find::name};
  }
  return @files;
}
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