In olden pre-YouTube times, a girls' day at the mall ended with friends gathering in a bedroom to model and compare their treasures.

These days, a teen-girl shopping trip is often followed by a "haul."

Shorthand for the homemade videos that detail the resulting spoils - from the skirt found on sale at Target to MAC's latest lip-gloss line - the vlogging trend that caught on about two years ago now results in more than 100,000 on YouTube. It's a natural outgrowth of the Internet oversharing that's second nature to this age group.

"It's just a social truth that we love to share our finds," said Louise Dengerud, an account director at Olson, a Minneapolis creative agency that uses social circles to promote clients' products. "It's a more female psychology to want to share that you don't find in the straight male culture, except around tools and electronics. Guys would probably watch that kind of haul."

Some hauls are simply short "I got this" recitations. Others give product reviews or show how to apply makeup or create hairdos. It's inane, but innocent enough, when tweens and teens hold up a blouse and say, "I found this at The Gap on sale for $25!" But some hauls range from vaguely inappropriate - suggestive modeling of short shorts - to downright creepy, like advice on creating "Valentine's Day eyes" from a girl who's not yet old enough for a driver's permit.

Another murky ethical issue around hauling is that, like many trends before it, it's gone commercial. Young fashionista haulers with thousands of online followers capitalize on their popularity as a way to score freebies or paid-endorsement gigs from clothing and cosmetics companies.

The viewer perception of a girl "just like me, or maybe a little cooler than me" is more effective in swaying buying choices than any child actor in a commercial could be - so much so that in December 2008, the Federal Trade Commission ruled that haulers must disclose to their viewers which products they've been given free.

The most talked-about "haul queens" to date are sisters from Tennessee, 16-year-old Blair Fowler and 21-year-old Elle, who are so successful that they've hired a Los Angeles agent. Their YouTube vlog channels, juicystar07 and allthatglitters21, have a combined half-million subscribers, so trendy product pushers are practically hurling their goods at the Fowlers, hoping they'll get a thumbs-up. Like other successful haulers, the sisters also get money from online-ad revenue, which they split with YouTube, and fees for reviewing products that seem to blur the lines between independent observation and paid endorsement.

A lot of companies and brands are mining this data, Dengerud said: "Word-of-mouth marketing is at the core of all real successes; technology has just enabled us to do it on a broader basis. The haul vlogs are like focus groups you don't have to pay for, and way more relatable than a commercial. It's so easy to find out what people think of your products or store. All you have to do is start surfing."

The secret to the haulers who really take off and attract tens of thousands of followers is a combination of "enthusiasm, honesty, insight, and a sense that they did your work for you," she said.

Michelle Fitzgerald, a partner at Brew, a Minneapolis creative-communications agency, expects the credibility of hauls to eventually diminish.

"The Web has made it so that we actually do trust strangers to tell us what's good or not," she said. "But the more people who know that these teen haulers have been incented to swoon over a product, the less effective they will be at influencing others. The key will be for haulers to show some objectivity and inject their real opinions about the products and services marketers are pimping. Without that, consumers will quickly learn to see haulers' opinions for what they are: another form of advertising."