Okay, this was written after watching "The Merchants of Cool," a Frontline program about this subject, so my opinions and examples may be informed by that show. I'll do my very best not to parrot the program.
Cool Hunting describes an under the radar market research technique primarily employed by large media companies interested in selling to teenagers. The short version of what it is is a method where teams or individual market researchers will go to places where teens are likely to be "looking cool" -- e.g., concerts -- and interview and photograph them. They are on the lookout for the 2% of teenagers who constitute the real trendsetters, the teens who are embodying at least part of the next "big new thing" which will be popular among the mainstream in 6 months. By gathering a mountain of this data, the marketroids can extract the common elements, then incorporate those ideas into next month's fashions, mtv show, and radio playlists.
An actual example of this marketing is MTV, who conducts interviews with normal kids (who are actually very carefully selected to be "perfectly normal") to determine what they are thinking and listening to and wearing. The interviews are filmed, cut down into MTV-style videos, and shown to the executives who decide what's to be put on TRL and which mook should get his own show next.
The end result of this type of marketing appears to be a viscious feedback loop in teen culture, wherein marketers set the bands on TRL, the feel of the show, and the image for the spring break crowd. Teens watch the show, incorporate the images and styles and bands and attitude into their "look." Despite what the trendsetters think, their style is informed with the popular culture's movement. The cool hunters track this next generation of cool, report it to Viacom and Disney. At the end, we have all the little girls wanting to be Britney, all the little boys wanting to be like those cool Limp Bizkit boys; spring break become an imitation of the whipped cream bikinis and wet tee shirt contests the high school seniors saw last year on MTV's Spring Break special. All the while, Limp Bizkit exhorts the boys to "break stuff" and Christina Aguilera invites the girls to show off their midriff and shake their tush to get anywhere in life. The culture devolves (or has devolved) rapidly into the absolute safest, easiest, lowest common denominator in order to provide a quick, safe medium with which to communicate what the teens should spend their considerable buying power on.
Oh, and to the softlinker itching to add Rampant mass consumerism is so evil. Hey, can I have a sip of that Frappucino? -- don't bother. I already added it.