even if Google are planning to "do no evil"
Google is a marketing company. If marketing is "not evil" is already subject to discussion. Marketing is usually pro "whoever pays for it".
They collect data and care absolutely nothing about privacy. They can and will scan everything they get hold of. Facebook is even worse though.
Keep in mind that many of these companies offer services for web masters that will notify them when you hit the pages. So even without the redirect they may gather the information.
Similar things apply to almost all of the "social networks" and other free services. I think most people are not aware that there are companies who are systematically monitoring and evaluating this data even in real time. The results may then be ranked according to sentiment (!!!), social rank (number of followers, number of friends, number of replies, whatever comes to mind) and put automatically into CRM queues.
There is nothing inherently bad about it. The nasty thing is that this happens behind people's backs.
I think it all boils down to what Noam Chomsky described quite a while ago: chomsky.info : The Noam Chomsky Website. Just that the "social" technology pushed the whole thing one level higher.