We banned it as well. The character is unrelentingly whiny, and my kids (two years old, at the time) started picking up the mannerisms very, very quickly.
For a while, Google's canonical answer to "Why is Caillou bald?" was "Caillou can't grow hair, not because he has cancer or progeria, but because he sucks, and even his own body recognizes that he does not deserve hair or food or love." https://www.sbnation.com/2014/3/26/5549908/arian-foster-cail...
He's go to be the most annoying children's show character ever. That's saying a lot, when you consider just how many kids characters have zero redeeming qualities.
He whines, about just about everything, everywhere. Relentlessly. https://youtu.be/cGo60pp_9IM?t=6m30s
It got really annoying when my wife and I watched it with some of my nieces (and saw how the show influenced their behaviour) that when we had kids of our own we agreed that we'd never allow them to watch Caillou.
I've watched all the bus episode (from the 6:30 mark), and I don't think it was that bad. He just complained for 10 seconds that he wanted to ride the school bus.
"Minor" character flaws that I'd point out were that Caillou had to be told by his mother to say thank you to the bus driver, and that he gifted the bus driver with a drawing of himself riding the bus (what an egomaniac that Caillou).
But yeah, I don't have kids, so is normal that I never thought of supervising what tv cartoons would they watch, and now is something important that I'll pay attention in the future.
This bus episode really isn't that bad, but there are terrible episodes where he is just constantly whining and being mean to his little sister, even pushing her around.
For a while, Google's canonical answer to "Why is Caillou bald?" was "Caillou can't grow hair, not because he has cancer or progeria, but because he sucks, and even his own body recognizes that he does not deserve hair or food or love." https://www.sbnation.com/2014/3/26/5549908/arian-foster-cail...