Regardless, I'm pointing out the effect that just adding a couple more points will significantly increase the results. This is more-so a proof that the example is not significant because of the variance of adding another term. Good point, though.
I don't understand why someone would google for "facebook" in the first place (or at least, more than once). I wonder how accurately the web search traffic for facebook correlates with its actual usage/popularity.
A surprisingly large number of people always use their favorite search engine to get to other sites. They Google for "facebook" or "www.facebook.com". This goes for all web sites.
That's the nice thing about firefox. Once I visit a site a few times it comes up in a list when I start typing the site. And if it's not in my list, I can just google it right from my address bar.
I think some of this is driven from the google toolbar, which many people confuse with the address bar.
On a side note, what really boggles the mind is the number of searches for "google" or "google.com". According to the Keyword Tool, there were approximately 30mil exact searches for "google", and 7.4mil searches for "google.com"!
Some browsers will google search a term typed into the address bar if it is not a fully specified URL. On my system, if I just type "google" into an address bar, it directs me to the google search for "google".
A lot of people use google instead of typing in URLs. So to get to facebook, people go to google, then type in facebook or facebook.com, and then go from there.
Another thing to note which significantly alters the analysis is that facebook is a brand in any country whereas porn (or the other such search terms) come mostly from english speakers.
Just a thought -- you get what you measure.