Advertising is always trying to manipulate us. That's why ads sell, they are made to manipulate the mind of the consumer so that they become motivated to purchase a product. However, I believe the idea of "subliminal" advertising is bogus. Though hidden messages in commercials and even movies are known to exist, the average consumer is not necessarily aware these bits of "subliminal" hints are even there.
It's a known habit of our culture to read too much into things, so I feel the same goes for advertising. Yes, ads do use subtle clues to persuade their audience to feel a certain way about their products, or to commit a certain action. For example, using sexually suggestive images is nothing new, especially for ads that involve things like lingerie or cosmetic products. However, when it comes to covert messages in ads, I believe that for most cases what may seem "subliminal" is really just a matter of a person's perspective. We are hard-wired to find controversy in things, so it makes sense people would want to pick apart ads and decode hidden messages in them when in fact there aren't any.
Had the false study done by James Vicary in 1957 been a real thing, I think that even then, not everyone would pick up on the "messages" for popcorn and Coke inside them, at least not enough to cause mass-hysteria over the topic of brainwashing. The closest thing we realistically have to subliminal messages is priming, which does influence the thoughts and actions of the consumer subconsciously, also influencing how ads are interpreted by their audience.
Still, according to this article on explorable.com, priming can have a short-lived effect on a consumer's buying habits, but has not been proven to change people's way of thinking or behaving for a longer period of time.