Not all ads are necessarily bad. Eg have you ever seen an ad for an event in your town? Maybe a play or a concert you'd want to see. Those to me feel more like "public notice: thing is happening" and every once in a while I'll actually go buy tickets. But technically, those are ads, just not the kind of exploitative ad you are talking about.

A good ad informs, while leaving the decision up to you. A bad ad distracts you with garbage and/or tries to get you to indulge in your worse impulses