I've found this and it gives me no comfort whatsoever:
http://www.zdnet.com/blog/facebook/facebook-fixes-cookie-behavior-after-logging-out/4120I have now proved conclusively that F/book keeps your cookies for
Days. Fortunately the Mac I was on earlier (when all this happened) had never had Firefox history changed from default. I had to go back FIVE
days to find a previous 3-second visit to f/book.
Therefore, despite having cleared cookies before I went there today, they had my browsing history nailed. From 5 days ago.
F/book has to be the most sinister place on earth. And thanks to this, my already understandable fear (from having been stalked on the internet a few years ago) is now reinforced even further. I have gone around the office fixing every Mac's browser not to accept 3rd party cookies, clearing history, and asking every time before accepting any site cookies. All thanks to F/book.
There are millions of people using that place who presumably have no idea what is going on, on their own computers, by them.
How stupidly naive they are, and I was.