I prefer to learn from good writing. I find bad writing too painful to read. Also, I worry that I will pick up bad habits. If you recognise the mistakes you knew them in the first place. I think "learning from bad writing" is a bit of a mistake.
I have experienced many bad drivers but I have yet to learn anything from it other than not to get in a car with them ever again. I could say the same about books/authors.
Stephen King says in his book On Writing "...often bad books have more to teach than the good ones."






