That incognito trick might work for the annoying stuff like embedded ads and stuff, but if you really want to be "covert", it's not the best tool. Stuff like your IP address, network routes, etc can still be kept and then the moment you lose discipline and use cookies, all that hard work to cover your tracks is undone. It's all about being able to identify the machine and the human. They don't need both to be present at the same time to do it.