I've chosen not to read the other answers so far provided, so I'm not influenced. What follows is my laymans opinion. Firstly, I think its a great question.
I think since the dawn of advertising, it has always been the case that the vendor has been trying to influence the sale of their particular product. I guess this seems rather obvious. Throughout the decades and centuries, this objective has never changed.
What has changed is that technology and social sciences, have matured and combined to provide a more sophisticated way of influencing. The greatest difference in the abilty, being that large corporations can now reach a world audience, thus exerting a greater focus on their product than would have been possible even only a few decades ago.
It is increasingly difficult to not be influenced by advertising and target marketing, but while capitalism dictates, which it does for much of the world, this type of marketing will always be acceptable, regardless of its ethics.
This said, I understand that in Holland (the Netherlands), government restricts advertising of toys and childrens things on television, at the very time that most children would be watching it! This responsible, governmental control over such things is an ethically sound approach in my opinion.
On a personal note, I think I think it is unethical to degrees, but then, providing the advertising is honest about the product it represents then I guess I can cope. Equally, can a trust that honesty will be the case. The cynic in me says 'no', not always!