Terrible in-game ads

Most ads in "free" games that have ads are absolutely awful. They are typically predatory, deceitful, and borderline (if not actually) scams. Do people keep buying ads because they actually see significant ROI, or are they hoping to see ROI because someone else sold a lie to them?

Or do they just constantly publish new games, perhaps even under different identities, in order to keep making money off fresh lies?

Eek.