There is a good chance that Facebook already knows you visited a particular site because that site is already serving Facebook content (via a like button, for example).
This is exactly why I use a different browser for Facebook than any other web browsing. As far as they are concerned, the only site I ever visit is Facebook.
Same with Google properties. I only use Chrome to visit Google properties.
As crazy as it sounds, I actually like the other trackers, because then I get more relevant ads. I'm also one of those crazy people that things adblock ruins the web (this opinion may be because I worked for a website that survived on ad revenue for a long time).
I'm sorry to be rude, but that strikes me as legitimately paranoid. Why do you care so much if Facebook knows that you visit sites other than Facebook?
I guess it depends on why someone uses Facebook. I (finally) got an account a while ago in order stay in contact with friends and former colleagues. My usecase of Facebook does not include me wanting Facebook to know everything I do.
Hence, Facebook lives in its own VirtualBox machine.
