What's worse is advertisers must know how annoying they are and how ineffectual they are. So if an ad annoys 10,000 people, and wastes countless hours of their lives taking up tv space or bespoiling the built environment but brings about 1 sale they're happy with that.
Terrible humans.
Good advertising works though. A well marketed low quality item will sell more than one nobody knows about. Carling sells a shedload more than in a month than much better beers combined will shift in a year.