I dont know about the ones i hate the most but those commercials that advertise shows that try to pull off that "Mysterious new show, we wont tell you what its about you'll just have to watch" crap. Just tell us what the show is about without revealing too much, how can you screw that up?

Also the ones that take some form of national folk song and use it to promote where theyre made or use some other traditional song (like a christmas carol or something) to show how they care or whatever. It's rather degrading