Great explanation, Susan, thank you. I definitely agree with you that grammar rules are often not well understood or presented, and I'd go along with the idea that teachers are to be blamed for it, not the rules themselves.
How many coursebooks do you know for instance that tell you some is used in affirmative sentences, and any in negatives and questions?
Yes, definitely. I have had trouble with that very example, but I have never encountered a book where a sentence like
Would you like some wine is explained as an exception of that rule. They just write the "definition" and we have to deal with troublesome questions if some students happen to ask them.
What would you put forward as "genuine" exceptions in the language?
I don't know actually, I hoped that you might know a couple of examples.
PS. I'm mostly teaching children and adults at elementary and pre-intermediate level