Of course, it is perfectly acceptable to enforce basic rules of propriety - for instance, I would not let Nadia wear a Catwoman suit to a funeral - but if it is just a matter of personal taste, I need to stay the fuck out of it.
When I was young, I saw the following horrors thrust upon my fellow children -
* a boy forced to wear extremely high waisted jeans, because his parents disapproved of the saggy look. They seemed unaware of the fact that there was a happy medium between tight cowboy jeans and jeans so low that the underwear showed.
* a girl who was not allowed to shave her legs until she was thirteen, even though she was hairy like a male yeti. She was mocked relentlessly. What was her mother thinking? What was she afraid would happen if her hairy-ass daughter shaved her legs? That she would contract tetanus? That she would turn into a slut?
* A girl who was not allowed to wear nail polish unless it was pink or red, because any other color was "inappropriate".
* A girl who was not allowed to cut her ridiculously long hair, because her dad wanted it long for some reason. She looked like she was raised on a polygamous compound, and she clearly hated it.
All of these are examples of parents forcing their taste on their children, to their children's detriment. Fashion changes. What was cool when I was young will not be what is cool when Nadia goes to school. And unless her clothing choices are offensive or dangerous in some way, I need to stay out of it and let her experiment with how she wants to present herself.
2) The kids who kiss my ass are not necessarily the nice kids.
We all knew those kids. They were super polite and perfect when adults were around. And in return, all adults loved them. "Why don't you invite Kid A to your birthday party? She's such a nice girl!"
But she wasn't a nice girl, was she, ladies? No. She was an evil bitch. But nothing you said would ever convince the adults in your life that she was anything but an angel.
3) The kid who has no manners is not a bad kid.
The kid who comes to my house and has no understanding of how to eat at a table, who never says please or thank you, who uses foul language, etc - is NOT a bad person. He is neglected, and possibly abused. Obviously no one gives a shit about him, and no one has ever bothered to teach the child how to behave. Lots of times, I've heard parents say that they don't want Such and Such KId to come to their house because she's rude and awful. They need to realize that A) If a child doesn't know how to behave, it's not the child's fault, and B) Allowing the child to hang around your home will help to teach that child how to behave properly. Children learn my example. If you ban the rude kid from your home, all you've done is teach that child that manners are the domain of snobby, exclusionary assholes, and she might not ever learn any better.