When I was in high school, I worked for a farmer whose primary product was hay, as he was getting old for dairy. He was able to correlate the value of $1 investment in advertising (mostly weekly newspapers and ads at horse facilities) to sales. He used a pencil, penknife (for sharpening) and a bound marble notebook from the drugstore to do this.

At the end of the day, there may be businesses blowing useless dollars on advertising, but businesses that don't watch their dollars don't tend to last very long.