Honest question for you and the others who feel the same: do you interpret any other idioms literally? Or, relatedly, believe a rhetorical question is expected to be answered?
I usually say, “Okay” or “Good” unless things are just unspeakable. Then I say, “Mmkay.”
(I don’t go into detail because things are unspeakable.)
These things, these little comments, are just things to grease the wheels of conversation. I don’t necessarily like my coworkers, but I’m stuck with them for eight hours, five days a week, or more. So we use these little niceties so we don’t kill each other.
Yep–one must recognize phatic speech, and not mistake it for serious communication.
phatic
adj
(Linguistics) (of speech, esp of conversational phrases) used to establish social contact and to express sociability rather than specific meaning
phatic expression
In linguistics, a phatic expression is one whose only function is to perform a social task, as opposed to conveying information.[1]
In speech communication the term means “small talk” (conversation for its own sake) and has also been called “grooming talking”.[4]
Similarly, the question “how are you?” is usually an automatic component of a social encounter. Although there are times when “how are you?” is asked in a sincere, concerned manner and does in fact anticipate a detailed response regarding the respondent’s present state, this needs to be pragmatically inferred from context and intonation.
I just prefer to try to be precise with what I’m saying and I think that a person who doesn’t recognise that this is actually a non rhetorical question that should be answered as such gives me an impression of not being all aware of what he really is saying.
As it happens I once said to a Chinese friend that it is a pity that I couldn’t say hullo to him in his own language. After a second’s thought he laughed and said that he doesn’t think of its literal meaning when he uses it, it is just a phrase, and I guess that it is the same with people saying “How’s it going?” in passing (for those who don’t know Chinese it’s ni hau (or ni hau ma if you want to be extra polite), meaning “Have you eaten?”, which I thought was a silly question to ask a restaurant owner. 
As for rhetorical questions I only answer them when I feel a bit mischievous.
Even a brisk"good Morning!“, to a depressed person, sounds like : " Why can’t you have a good morning like a normal person, or at least pretend to, you damned sourpuss?”
Best to just nod, smile and say: “Hi.” That takes the least out of a depressed/negative person to answer back. 
Is it polite to answer a “How are you” with just an “how are you?” Not “How are you!” with emphasis on the you, but just the same phrase in the same inflection?
Or is that the equivalent of trying to get out of someones way and ending up opposite each other in that mirror dance?
No. It doesn’t work that way in English.
Anyway, I don’t ask this question myself, but it is so ingrained in people that often I’ll say “hello” and be answered with “Good. And you?”
To be clear, “Have you eaten yet?” is a common greeting in Chinese, but it’s said “Ni chi le ma?”, or literally, something like “You eat already [question]?” “Ni hao” is also a common greeting. It literally means “You good”, but translates as basically “Hello”, or “How’s it going?” in the phatic sense. “Ni hao ma?” literally means “You good [question]?”, but it’s not really used as a greeting. It’s like *actually *asking “How are you doing?”, where you expect more than a perfunctory answer. So if you ask “Ni hao ma?”, it would be perfectly appropriate for someone to respond, “Wo bu hao” - “I’m not good”. But this is just my understanding; I am not a native Chinese speaker, so folks are welcome to correct me if I’m wrong.
It’s not impolite, it’s just that no one would say that. But what does often happen is:
“Hi, how are you?”
“Good, and you?”
“Good, and you?”
“Good…”
Cool. What did the sewage treatment plant operator say? Cause I’m guessing he’d have made at least a nod toward an answer. Although I could be quessing wrong due to being from the wrong time period.
(I’m not a plant operator, but my Dad was. So if we’re discussing levels, that’s the one I was raised in.)
I suppose that I learned them both so young that I just never stopped to think about it. One had a set answer and one was an actual question.
I’ll try to approach it that way from now on.
“how you doin’” or “how are ya” is a greeting, not an invitation to unload on me. 'course, this thread has reminded me of this:
'course, it also reminded me of when I was working as a pump jockey/garage monkey at a service station, I had a lady pull up and ask me to check her tires, then when I was done she told me she had just lost her son (in his 30s, I think) to a freak accident. what the fuck do you say to that? 
You say “Wow, that’s tough, but at least your tires are properly inflated. Have a nice day.”
I usually say “good” or “fine”, but if things are really shitty I would say “could be worse”, “not that good”, or “ok.” If they want to ask more questions that’s up to them.
Yes! Thank you. That was essential to the discussion. That’s what it’s all about.
In Chinese, the phatic question is “Have you eaten?” It is a conventional, polite manner to present yourself as ready to feed the other person if they’re hungry. Even though it isn’t taken literally. It’s one type of the necessary social glue to help hold society together.
In America, comparably, we present ourselves as caring about the other person’s well-being and willing to listen. Again, pretty much everyone with at least a rudimentary grasp of social interaction understands that it isn’t taken literally, but that it sets a positive baseline for everyday contact between humans.
Forgive me for bumping the thread, but something happened recently that reminded me of this thread.
Someone asked my friend how he was doing. He answered, “Can’t complain, and if I do, no one listens.” I thought that was clever.