It's come to this: No one is more willing to talk about acne than a musician.

With celebrity acne-fighter Proactiv's signing earlier this month of Justin Bieber as a spokesman, the teen star joins Katy Perry, Avril Lavigne, Sean "Diddy" Combs, Jessica Simpson, Alicia Keys and Mandy Moore as recording artists who have signed up to talk openly about "critters on their face," as Perry refers to it in her spot.

Video: Justin Bieber's Proactiv ad

Proactiv has made it lucrative for them to talk, signing multimillion-dollar deals for the biggest names. Bieber will get $3 million for his two-year deal, similar to what Simpson was paid, according to a cosmetics industry source. Perry and Lavigne are paid almost as much.

"We did it because the kid uses it," says Bieber's manager, Scooter Braun, who wouldn't confirm the $3 million price tag. "I never want to do anything with Justin's brand that isn't organic. He isn't manufactured."

Proactiv spends between $12 million and $15 million per year on endorsements, says Greg Renker, co-founder of Guthy-Renker, which markets and sells Proactiv. The guiding philosophy behind the endorsements is that Proactiv spends less on branding by signing an instantly recognizable celebrity than it would on billboards and commercials. (It still spends big on traditional marketing-$100 million annually-for Proactiv and the company's other products.)

"I love Julia Roberts but I've probably had 15 movie experiences with her in my lifetime," Renker says. "I've listened to [Perry's] 'California Gurls' every day since it was released. Consumers are connecting to musical talent multiple times a day in a way that is more than visceral."

IN THE SPOTLIGHT

Proactiv is the flagship product for the private, Palm Desert, Calif.-based company, whose yearly sales exceed $1.5 billion, according to Renker. Its lineup of other products include such celebrity-backed skin care lines as Heidi Klum's In an Instant, Victoria Principal's Principal Secret and Cindy Crawford's Meaningful Beauty.

Unlike those product lines, Proactiv was never tied to just one celebrity name and through the years has signed a range of stars: TV actors like Jennifer Love Hewitt and "The Office" actress Jenna Fischer, as well as movie stars like Lindsay Lohan.

But it's musical artists who have proved to be the most effective spokesmodels, Renker says, as campaigns with TV stars have often fallen flat while those with Simpson, Perry and Lavigne sparked a noticeable uptick in sales.

All indications are that Bieber will do the same. During the first day that his endorsement was unveiled, there were 125,000 YouTube downloads of one of his Proactiv videos and 500,000 views of his Proactiv clips, Renker says.

Internet appeal is largely why Bieber and other artists are so effective-roughly 60% of Proactiv sales come through Internet orders and artists are better at reaching online consumers than other celebrities, according to Renker.

Renker says it's partly because fewer people-particularly young people-are watching TV, so they're less likely to know, let alone feel connected to, TV stars. By contrast, they still know mainstream recording artists, he says, and repeatedly seek out their videos online so they have more connections with them than other types of celebrities.

For all of those reasons, Bieber, who was discovered on YouTube, is a perfect fit. Not only are his fans in the sought-after preteen/teen demographic, but they eat up everything he puts out online and follow him on Twitter, where he's an active poster for his 4.5 million followers.

Bieber's Proactiv campaign takes advantage of that, with shareable YouTube videos and plans for tweets that point followers to his Proactiv spots.

MODEL BEHAVIOR

It's a big change from Proactiv's original model of signing likable TV stars to do 30-minute infomercials. Proactiv launched 15 years ago featuring actress Judith Light, who told viewers about her adult acne in an era when most celebs were still going to Japan or Europe to surreptitiously hawk liquor, coffee and other products.

These days, joining with Proactiv has become a mark of success. Celebrity agents and managers regularly approach the company about endorsement deals, and the stigma over paid celebrity endorsements in the United States has all but disappeared in the last five years.

David Reeder, VP of Greenlight, a media licensing firm that works with companies and celebrities on endorsement deals, says the Internet has changed the rules. Fans were able to easily see advertisements that celebrities had done in Japan and Europe online. When there wasn't any fallout, stars began wading into endorsements in the States.

Artists have been newer to the endorsement arena, but they're quickly catching up. A study by Greenlight found a 150% increase in celebrity endorsements in advertising around the 2010 Grammy Awards-many featuring artists.

Artists have partly been pushed into it as they look for new revenue streams. But there's also been an attitude change, Reeder says.

"The idea of selling out, which was pretty fundamental to the world of musicians, has pretty much gone away," he says. "There are still holdouts, like Bruce Springsteen, but younger artists don't view using their image to sell products as selling out."

Next: Bieber's Flawless Skin Shifts Proactiv's Marketing Plan