I must remember never to ask BobK a potentially contentious question like that!
As a general rule, questions which start "Do you" or "Don't you" attract either "Yes, I do" or "No, I don't" in one form or another as part of the response. There can be ambiguity if you don't clarify with "I do" or "I don't" though.
- Don't you want pizza for dinner?
- Yes.
Does the response mean "Actually, yes, I do want pizza for dinner" or does it mean "Yes, you're right, I don't want pizza for dinner"?