Bartholomew Bear says "Nah" all the time and doesn't do what he is asked - ds did go through a brief period of imitation - but when he discovered that unlike George we would put him in time out - he stopped. Dh does still refer to needing to use a big voice - and ds responds to it.
Thomas the Tank Engine trains are often "naughty", but end up eating humble pie.
Jez Alborough's Duck is thoughtless and sometimes just plain nasty - leaving his friends in the mud when he could have taken them home. Ds noticed this the other day - and said he wanted to take the book back to the library because Duck wasn't a good friend. I have noticed that is the follow up books Duck gets him comeuppance with a flooded bathroom, or having to walk to the petrol station whilst the others go for a boat ride.
He says things from Movies that are not really appropriate "shut up" from Madagascar being the main one. We have told him that "shut up" is okay in the movie but not at home.
In conclusion - children will copy - it's how we deal with the copying is important. I would much rather discuss Duck's shocking behaviour and how it's not on, than those bloomin awful morality books they have in preschools and kindies. Though ds does love those too unfortunately.
I realise it must be difficult if your child is very literal though.