> The only things I can think of are how a user interacts with a page - I don't particularly think this is too concerning Except that many people don't want ot

> The only things I can think of are how a user interacts with a page - I don't particularly think this is too concerning Except that many people don't want others to know how much they read something... I don't care, but many believe that is private. > If this does turn out to be a privacy concern, browser settings/privacy addons could simply load all lazy images or images refered to in CSS/JS files on load which would nullify this technique. So you load more invisible pixel and make this even more effective as now you'll be able to get much more granular data, like the scroll position!