Google bought DoubleClick. They were tainted from then on, as far as I'm concerned. DoubleClick had a known shady history, and executives from DC moved into positions of influence within Google.
Of course, it's not all bad -- Chrome is very much an old-Google product, pouring innovation into a category that was content to slowly iterate. Android is another example of good-for-Google, good-for-everyone innovation. But those examples are getting fewer and further between, while copycat products are getting more common.