Some legal resource I found online says that in the US fraud requires: (1) a false statement of a material fact, (2) knowledge on the part of the defendant that the statement is untrue, (3) intent on the part of the defendant to deceive the alleged victim, (4) justifiable reliance by the alleged victim on the statement, and (5) injury to the alleged victim as a result. [1] Note that "material fact" here is a legally significant phrase, and implies a written agreement or some other mutually agreed to terms that establish the expectation - which never happened between you and the ad provider.
No matter how you slice it the user of ad nauseum is not committing fraud. This misinformation needs to stop.
Walk me through this, okay?
(1) a false statement of a material fact
The extension is telling the site, "I am this browser (user agent), requesting this content (what's behind this ad url), who clicked on this ad (calling the onClick handler of the element that has the ad."
That's not true. The user did not click on the ad.
(2) knowledge on the part of the defendant that the statement is untrue
The user knows they did not click on the ad.
(3) intent on the part of the defendant to deceive the alleged victim
Everyone in this thread is saying it's to confuse the metrics, and some are saying it's to purposefully take money from the advertisers.
(4) justifiable reliance by the alleged victim on the statement
The vast majority of HTTP GETs to URLs that are only found as href on Ads are requested because the user clicked on the Ad in their browser. Can you name even ONE other time a browser follows the onClick event on an Ad?
(5) injury to the alleged victim as a result.
Money.
So, walk me through how this is not fraud?
First, a GET request is in no way a statement that the user intended to view an ad: is accidentally clicking an ad fraud? Of course not.
Second, a GET request is not even an indication that the user clicked on some element. It's not even a statement that the user requested a particular resource. Indeed, when the ad itself is requested you could hardly call that user-requested; if your analysis were correct I see no reason we couldn't extend it to say that ads themselves constitute a fraudulent statement that "this content is something you requested".
Third, even if a GET request amounts to a statement of user action (if not intent), adnauseam's actions do not constitute a false statement of user action/intent. There are lots of ways to activate the default onclick handler; physically pressing a mouse button is only one of them. Trackpads and touchscreens are other ways; are they fraudulent? Keyboard shortcuts and other keyboard navigation are yet more, are they fraudulent? No, of course not, since they accurately represent user actions. Installing adnauseam is just another method of performing the same action, clicking on ads. It accurately implements the intent of the user, more so than clicking, which can be accidental.
IANAL, but based on your own criteria, without a false statement of material fact there is no fraud.