&gt; Google can never necessarily know what you want and can never truly know you achieved your goal, so you could not train it properly.<p>They do have some amount of confirmation. All of their search results are redirect links, so they&#x27;re tracking which links you click on. Based on the timing of those clicks, they can tell if you clicked on a result, left that site a few seconds later, and then clicked on another result further down the page, which probably means the first result didn&#x27;t give you what you want. It&#x27;s not perfect but it&#x27;s still potential training data.<p>If that site has Google Ads or a Google &#x27;+1&#x27; icon, they can get slightly more information about how you spend your time on that site. I don&#x27;t know about the legality of this but it&#x27;s technically feasible.