http://www.perlmonks.org?node_id=728722


in reply to Re: Dealing with binary data and WWW::Mechanize and encoding stuff
in thread Dealing with binary data and WWW::Mechanize and encoding stuff

That was the clue I needed. The underlying content method from HTTP::Message will get me the original unmolested byte string from the server. So all I have to do is use $mech->response->content instead of $mech->content, and it works perfectly.

Thanks!