Our culture is inundated with propaganda and marketing, and not just of the corporate variety. It seems to me that the marketing done by the big corporations is as much or more of a response to the current teen culture versus the current teen culture being a response to marketing, though. But no doubt, the two are intimately linked. In today's information overloaded society, there is no insulation, whatsoever, from full frontal assault "marketing". And by the time your kids are teenagers, they have long since formed the cognitive skill sets, values and ethics that will filter how they respond.
It isn't corporate culture that is destroying your/our youth, though (IMO) -- it is a general lack of any other substantive culture to fill the void, and a vacuous culture where kids are raised and educated without sound moral values, and without the ability for critical thinking and sound decision making. The blame for that resides primarily with parents and our current public education system -- not corporations. Don't blame the predator for going after the easiest prey.
Corporate culture? Corporations don't have culture. Corporations respond to, and yes, "exploit" (some might say profit from) cultural weaknesses and trends. Air rifle manufacturers exploit my love for gadgetry and shooting. Drug dealers exploit the junkies insatiable habits. Brokerage companies exploit the desire to grow wealth. Corporations exploit people's desire to be healthy. . . or to look good . . . or to grow hair . . . or to be ready when the time is right . . . or to play the next cool video game . . . or to have the best laptop computer or fastest car. Politicians exploit people's needs and desires -- to have a cleaner planet . . . or to save the baby seals . . . or to prevent global warming . . . or to have better health care . . . or to improve education. Don't for a moment think we adults are exploited any less than our kids.
You are absolutely right, though. Don't want to be exploited? Better start thinking critically and asking what is behind the message every time you are being "sold" something, commercial or political -- to what purpose?, who benefits?, what are the alternatives?, how is that message biased and why? (it is always biased).
