Quote Originally Posted by 2006 View Post
I mean are the students reading our posts really supposed to remember that it would be quite okay to say "don't say nothing" when speaking to people in/from East London and East Anglia, even though it would be best to say "don't say anything" in most other places?
That's for the learner to decide. As a teacher the best I can do is offer students variants that they may come across. Whether they feel on a personal level the variant is appropriate or not is a choice/judgement they will have to make. After all, they are adults, and learning to be open-minded comes with the territory.

Quote Originally Posted by 2006
And are they really going to understand/remember that "if there is very heavy stress on "don't" or a specific plaintive stress on "nothing," then it would be a grammatically correct way..."? Or will you just confuse/overwhelm them, especially middle and lower-level learners?
Again, I don't presume to know what is best for them; I teach English. They decide what is or isn't useful, relevant or important to them.