It's pretty tough to stump the band around here, isn't it? : )

Doing as you suggest does produce the sought-after output:

mojodaddy@muchomojo:~$ perl -s foo_eq_bar.pl -foo=bar
true
woo
woo-hoo
woopty-doo
[download]

Still, I can't help wondering why only the "if ($foo eq 'bar')" script was affected while the "if ($foo)" script did what I expected regardless of where I put the -s.