> while not breaking most sites.
You should use RefControl <
https://addons.mozilla.org/en-US/firefox/addon/953 > to spoof referrers headers, not Polipo, as RefControl does HTTPS and HTTP. The nice thing about RefControl is it can be set to the <forge> option which will use the current site's own root as the referrer. So Incognito would have full (HTTP/S) referrer spoofing and it should not break any sites (I've yet to break a site with RefControl).