Interesting Powerpoint on how institutions see 'Youth' in terms of qualities and values in order to sell things to you. Flip to slide 19 to see what it says about 13-17 year olds, apparently it's all about creating an 'identity'.
http://www.slideshare.net/guest10a9e56/youth-marketing-a-guide-to-understanding-youth-development-phases-by-dan-pankraz
Here's two articles looking at the effects of marketing on youth culture one a bit wordy and one just getting to the point.