After our tea I brought down the easel from upstairs and my boy and I painted. I would be told to paint something, usually a  T rex and then he would splurge paint all over it so it was a mess. I admit that this was ever so slightly infuriating. He would never say that it was a good likeness before he ruined it. So I told him his pictures were shit. I'm joking. But they are shit. 
Nursery are not allowed to say anything they create are anything but wonderful. But this will deceive them into thinking that they are good at stuff when they are not and then when they realise  that they've been lied to they will harbour a hatred for the world and grow up to write a blog about everything being shit and not be great at people skills.
Sounds famiar.