I'm highly skeptical, in that I believe the nature of ads makes this inherently unfeasible.
The point of ads is to be seen by as many people as possible. In dramatic terms, you could say the purpose of ads is to invade your mental space against your will on behalf of product makers. How could that ever be ethical?
That aside, ads also present a conflict of interest for content makers. You want your site to be nice and high-quality. But you need money, so you put up ads and comprise on the aesthetics. You want more people to see your ads so you're tempted to make more content, or arbitrarily divide your content into smaller pieces (fighting the end user's ultimate desire which is to peruse your stuff).
And then there's the whole "biting the hand that feeds" problem. I personally don't believe anyone showing ads can be truly objective regarding them. So maybe Google is evil, maybe not, are you going to turn down their money either way? Most smaller ad networks seem shady to me.
I think this seemingly theoretical problem is why ad blockers are still on the rise, going so far as to be baked into browsers (Brave on mobile is awesome). Not only do people dislike ads, I think they don't trust advertisers, and I think most users nowadays are aware of these ethical conflicts at least on a semi-conscious level.
In short, this is why I've personally made a promise to myself never to rely on ads. Maybe that means I can't get rich off of "killer apps", or even earn a living. But part of me believes that anything useful is worth paying for, so I'm focusing on building something useful.
Edit: Didn't mean for this to turn into a rant. Oh well!
Considering malvertising is a thing, attempting to spread malware through ads, users shouldn't trust advertisers.
I don't just run an ad blocker to prevent annoyances, I do it to increase security.