Clearing your cookies or using a generic cookie against Google is only minimally helpful.
Every computer that hits against Google, including for Google Talk, Gmail, Google Earth, Free Republic, etc, has its IP address saved by Google. If you run on Comcast cable, for instance, you are in an IP address range that, at its most, is likely randomized to 256 addresses in your immediate neighborhood. You keep this address on your modem, typically until the power goes out. So you need to reset your modem at least daily, right?
Nope, that won’t help. Because even if you did, you will have visited say, five sites that are your normal sites, under any IP address you had. Guess what? Google knows you visit these sites because of Google Syndication and your search clickthroughs. You have an easily identifiable routine that quickly makes your visits today to Free Republic and elsewhere line right up with the recorded behavior of a slightly different IP from yesterday (say, that wouldn’t be YOU, would it?). Therefore, you are incredibly easy to track just by Google.
Google says they anonymize the last 256 bits of an IP address after many months, but as I just showed you, you are still easily found and lined up against what you do today under a different IP address and a different cookie.
Oh, and many people are using Google Chrome as their browser, or using Google as the default search in Firefox. On top of that, Google Android phones all phone home for everything you do. Do you access Hotmail on your phone using XXX@hotmail.com as your address? Google may know this, and definitely knows this if you set the Gmail account you use to pull your Hotmail emails into it for easier viewing (Google wants you to use them as the hub of everything).
Starve the beasts by the tools I mentioned above.