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Sorry but don't believe you about google toolbar. I had a private page with no links in or out and yet it appeared in google search. It was not guessable and there was no chance for a referrer link. The page was never shared with friends nor accessed outside my own computers. I only found out when a friend searched for his name and the page appeared as it was my phone list
Multiple people have run controlled experiments like I described in http://www.mattcutts.com/blog/debunking-toolbar-doesnt-lead-... The most common way such "secret" pages get crawled is that someone visited that secret page with their referrers on and then goes to another page. For example, are you 100% positive that every person who ever visited that page had referrers turned off on every single browser (including…
Referrers only get shared through links. There were no links to or from that page. Going to a page and typing in new URL does not provide a referrer.