I loathe Peppa Pig. DS has just started to like it at 4 (mostly cos he hasn't been able to see much of it thanks to parental loathing). But I sit and comment on George's appalling cry-baby behaviour, tantruming when he can't get his own way; and Peppa's bossiness and annoying behaviour. Daddy Pig is a figure of fun which isn't helpful in most cases, ditto Grandpa Pig. And as for them all throwing themselves onto their backs and shaking the floor with laughter, pah.
DS has taken to throwing himself to the floor to attempt a tantrum, but I will not allow him to do so. I'm sure if he was a different temperament, he would carry on regardless of what I think/want - but he's mostly pretty good about stopping.
However, he has started with the "I don't like you any more, you're not my best friend" rubbish to both me and DH now - could just be a coincidence, might not be.
There are a lot of children's programmes that are unhelpful in terms of demonstrations of poor behaviour though - a severe lack of manners in lots of them for starters. But then I am an old gimmer and think that childrens' programmes should set a good example - no doubt they'd be bored by that and refuse to watch them (a GOOD thing, probably!)