Biology is not your strongest suit, I see.

Hey, I can sell you stuff that used to be part of a star. Can't tell you which star though, it exploded some time ago. And you know what, its elements probably came from an even older star. And that exploded too! Let me know how much you want.

Indeed, but "types of users" and "buying habits" only emerge *after* collecting enough detailed data. I do not beleive they start out with a specific classification in mind.

They probably count like:
1,2,3,4,5,10,11,12,13,14,15,20,21,...
Which is smart, because their "10" is divisible by 2 and 3.
(if we had 12 fingers doing math in our head would be a lot easier)

A subtle difference in taste is enough for you to not save an ecosystem ? Maybe we should not be so snobbish food if it can help the planet. I stopped eating meat even though I find it tasteful. If farmed fish would indeed be a solution to keeping the ecosystem in balance, then surely this small sacrifice in taste is worth it ?

Parent isn't flamebait. This happened to a friend (he installs networks, firewalls, etcetera for a living, so I suppose he knows his stuff): installed a new webserver on a new dns that was never on the internet before. To test firewall settings he surfed to a URL on that webserver using chrome (it happened to be installed on that client's pc). Half an hour later he sees google spiders hitting exactly that rather obscure URL... Freaks me out!

Use Firefox with the NoScript add-on. http://noscript.net/ It blocks/unblocks javascript exactly the way you want it. And makes surfing safer in general.
Another interesting add-on is CustomizeGoogle. http://www.customizegoogle.com/ It can block cookies being sent to Google Analytics and it can anonymize the Google UID.