A bit of a dust-up on Ken Levine's blog last week, when he ranted about the problems he's seen over the years with stage parents that put too much pressure on their kids. The post got picked up on the Huffington Post, where it came to the attention of Diana DeGarmo's mom. In the comments, she posts about the sacrifices she made to help Diana achieve stardom on American Idol. She also takes offense to the idea that all stage parents harm their kids on some level.
She's probably not the right person to target for such criticism -- the "stage parent" tends to start with kids much, much younger, with the goal of breeding and grooming a hyper-celebrity. (Just watched Blades of Glory last week, and the extreme version of this plays out when Jon Heder's father "un-adopts" him and strands him by the side of the road for winning a silver medial instead of a gold.)
The crucial factor is whether the stage parent, often acting as teacher, coach, and manager, is making decisions based on their own passion or their child's passion. I often encounter parents who have done a great job taking on the role of manager for a teenager's music project. The kids are old enough to express their level of passion and commitment, and the parents can be professional and detached enough to treat what they're doing like a real job.
That's the defining ability of any manager, really -- to put a client's interest ahead of their own. Managers who understand the nature of that kind of sacrifice are really the ones you want to look for, which is why I often suggest that bands recruit friends or family members instead of industry veterans.
On the flip side, any manager that exploits a client solely for their own gain has a higher power to answer to -- especially if that client is their kid.