I will agree that people ask "How are you?" for sole polite standards, they do not really care.
I've noticed that if I ask someone (as I'm walkin' by) "How's it goin'?" - they say "Good!" or "Fine!" and then they ask "How about yourself?" walking away. There's no room in there for anything, it's just common to say "Good!" or "Fine!"
I almost never give out typical answers, unless I'm in a hurry.