A book without potty humor is like a banana split without hot fudge. It can still be good, I suppose, but you kinda get the feeling that something is missing.
Most kids are smarter than most grown-ups. Kids see the world in black and white... They look through all the garbage and see a world run by fools and dullards and lazy people. And there's nothing they can do about it because they have no power.
These 'mistakes' occur in my books for a reason. I have an agenda: I'm secretly trying to inspire kids to create their own stories and comics, and I don't want them to feel stifled by 'perfectionism.'
Once I have the story in my head, I write it down. The illustrations usually come last.
I think every character I've ever come up with has been based on someone or something I've known.