You also have to think about tracking on the readers' side of things. If you read something on Facebook or Google+, you can count on that being tracked and adde

You also have to think about tracking on the readers' side of things. If you read something on Facebook or Google+, you can count on that being tracked and added to that system's profile of you. If you read something on a blog, and block things like Google Analytics, it's harder to passively track.