This an interesting topic. I am one of those 'fine' people unless you are a close friend or relative. (And if I don't like or trust you, you'll never get more than a 'fine' from me.)

I agree with DJ: In my experience, the 'how are you?' question is more of a conversational habit than a request for anything meaningful, so I assume a quick, pleasant answer is all that's needed. To be honest, if it comes from someone I barely know I find it kind of annoying and insincere. (I am mindful of the fact that people from different parts of the US have different conversational habits and people are just being nice, but doubt that they're really interested.)

I do know some people -- one relative in particular -- who will launch into a half-hour list of complaints and grievances, so I don't call unless I'm mentally ready for the barrage. But that's just the way she is.

You raise a good point, though: if we find ourselves talking a lot and listening little, it might be time to check ourselves even if it's not in response to the 'how are you?' question.