This is culture-specific! I know a couple of cultures where it's polite to offer (without actual intention of following through), and the expectation is that the person being asked also declines - out of politeness. Think of it as the equivalent of the American "How are you?" scripted exchange.
I think India has (or had) a three level rules where the first 3 queries were just polite to show some kind of friendliness. After that your in honest/genuine interactions.
