Saw the show. Calliou is a whiney little bitch, and he's a bad influence on children. The parents tolerate his behavior and let him get away with it, which teaches children to do the same.
He is a horrible role model for children of that age. He teaches kids that they can whine, yell, and throw tantrums to get what they want. Yes, kids are brats at that age, but it's up to the parent to teach them otherwise. Caillou does the opposite and reinforces that behaviour.