Really not what I meant

I'm not much with the small talk and niceties. I'm bothered by the vagueness when someone tells me to "have a good one" (a good what? Day? Weekend? Meth amphetamine bender? It's annoyingly unclear...), and I'll never ask "How are you?" unless I actually want to know or I really can't think of anything else to say.

Most of these niceties occur in auto-pilot mode. The asker isn't really thinking about the greeting or question as (s)he poses it, and the replier is equally inattentive in return. Still, it would be nice if I could abide by the simple rules of communication in these tiny interactions and not reply in ways that make absolutely no sense.

For example, when the cashier at Rainbow Foods says, "How are you?" the appropriate reply is any of the following: "Good, thanks"; "Fine, how are you"; or "Oh, you know--can't complain." The appropriate reply is not, on the other hand, to snap out of a haze and say "Hi," and then immediately replay the scene in my brain to realize "Hi" was not the opening line that was presented to me this time around.

I really hope that cashier didn't do a similar replay when I offered my reply, because to follow "How are you?" with the one-word answer "High" is really not what I meant to tell her about my life.