With user agent switcher plugin for Firefox you can now browse just as a googlebot and enter sites that are normally closed down to the public and require registration.  These sites are still open for google to spider them and if your a google bot then you can enter them just as easily for free. 

https://addons.mozilla.org/en-US/firefox/addon/59

Descriptioon: Googlebot 

Enter the following as a user agent.

Googlebot/2.1 (+http://www.googlebot.com/bot.html)

And now set it from the menu to use Googlebot then go to a forum that’s usually restricted to browse freely. 

Surfing As GoogleBot – Enter sites that usually need you to signup or pay for FREE