NEW YORK -- "I think sometimes young artists get to that (frustrated) point because they're young and it's a lot and it gets overwhelming. I don't think Justin Bieber is at that moment, I just think he had a bad week. That kid's a phenomenal artist, he's such a hardworking person, he's such a good kid," said Herbert.

But he acknowledges that for young artists, the pressure does sometimes lead to meltdowns: "No one's a machine - we're all human."

Spears became the poster child for that after she shaved her head and lost custody of her children, and more recently Demi Lovato checked into rehab because of an eating disorder and self-mutilation, though both have released successful music since. And many young members of Hollywood have been rebellious, used drugs and watched their careers falter, from Mackenzie Phillips to Corey Haim and Corey Feldman.

Carter said his bad attitude began to affect his business, and young singers must think twice about their actions even when they're at a breaking point. He says he's now working to rework those lost relationships.

"I probably messed up a particular movie I was going on an audition for because I showed up late and people looked at me like I was disrespecting them when really I was just out of my head," he said. "I've been for years right now scrounging and clawing and proving through my work and staying away from alcohol and trying to be the best person I can be to make up for all the things I've done, and that's been hard."

While Bieber, who was raised by a single mother in Canada, has held on to a pretty squeaky image, last year began to suggest some troubles: He vomited twice onstage during a concert in Glendale, Ariz., he was cited for speeding on a Los Angeles freeway and Los Angeles County Sheriff's investigators questioned the singer after he reportedly scuffled with paparazzi who tried to photograph him and then-girlfriend Selena Gomez as they left a movie theater.

"What he's going through ultimately is just the passage of adulthood and to go through that with this kind of scrutiny - it's hard," said Bill Werde, the editorial director of Billboard. "He's going to have to decide if he wants that or not. He's going to have to decide if he can handle the sort of bad that comes with the good."

Both Carter and Wahlberg are reluctant to give advice to Bieber simply because when they were in his position, they wouldn't have listened.

"The facts are that he's going to do what he wants to do," Carter said. "What happened to me when I was that age was the same thing - it's power. Your parents are telling you, 'Please don't do this, please don't do that' and you're looking at them going, 'Who are you? I am me.'"