$mechanize->add_handler("request_send",  sub { shift->dump; return });
$mechanize->add_handler("response_done", sub { shift->dump; return });
[download]

I get a lot of output that looks like this

GET http://www.example.com/
Accept-Encoding: gzip
User-Agent: WWW-Mechanize/1.60
Cookie: customer_type=IndividualUser; landing_page=original
Cookie2: $Version="1"

(no content)
HTTP/1.1 302 Moved Temporarily
Cache-Control: no-cache
Connection: close
Date: Wed, 15 Sep 2010 07:22:30 GMT
....

(no content)
HTTP/1.1 400 Bad Request
Cache-Control: no-cache
Connection: close
Pragma: no-cache
Content-Length: 2815
Content-Type: text/html; charset=utf-8
Client-Date: Wed, 15 Sep 2010 07:22:32 GMT
Client-Peer: 159.156.152.18:8080
Client-Response-Num: 1
Proxy-Connection: close

<style type="text/css">

(+ 2303 more bytes not shown)
Error GETing https://www.example.com/dashboard: Bad Request at SiteScr
+aper.pl li
ne 22
[download]