Pattie Mallette may be afraid to say too much to her son, lest she come across like an overprotective mother.
But Leif Garrett has no such concerns.
The 1970s teen heartthrob offered up some free advice for Bieber in an interview with Fox News this week, telling the network that young stars should not "believe [their own publicity]."
"Sussing out who your real friends are is full-time work. Every scum bag, every drug dealer, every chicken hawk wants a piece of you," Garrett said, unintentionally warning Justin about Lil Twist.
Garrett acknowledged Bieber's impressive charity work, but also went on to explain the pitfalls of fame at such a tender age:
"When you've got that sort of power at that young age, and everything at your doorstep, you put out that bad boy image. At that age, testosterone, hormones, all of the money, you see what else you can get away with."
So far, Bieber has gotten away - in the eyes of the law and in terms of maintaining a passionate fan base - with allegedly spitting on his neighbor... doing drugs on his tour bus... and peeing in a mop bucket, among other acts.
He also remains on a roller coaster ride with Selena Gomez, a relationship to which Garrett can relate because he dated Nicollette Sheridan in the early 1980s.
"Fame, money is what tore us apart," the former singer/actor said. "Nicolette just started modeling. My career was pretty much there. We would get along great or clear rooms. That's the whole thing with Justin and me. There was no in between...really good or really naughty."
That does sound about right.
Let's hope Bieber ends up on the side of really good in the long run.