I have run into the scenario of checking an end user’s computer for signs of p0rn, or surfing p0rn sites, and seen ambiguity introduced by popups from sites that are not p0rn per se, or clicks that were unintended and aborted. Obviously, malware can not only cause popups, but also download files nefariously.
This is an extreme cautionary case, in which a worker was fired for child p0rn, had his reputation ruined, faced criminal charges, and was found to be innocent. Tech support completely failed and even helped persecute him. That’s bad.