The worst[1] advertising is the kind that convinces you you have a problem you don't really have. It aims to make unhappy with what you have or who are when you would otherwise have been content.
Sometimes it seems to me like our society gets shaped more by the worst kinds of advertising than the best.
[1] By best and worst, I mean most beneficial to the person/people viewing the advertisement. An advertiser or deodorant executive would probably have a different opinion on the matter.