Bad Manners and Brimstone

Store clerk: "Hi, how are you?"
Customer: "Does this come in red?"

To me, that is a little rude and disrespectful, because it ignores the human gesture the clerk made and speaks only to how the customer wants the clerk to serve them. 

"Fine, thanks.  Does this come in red?" takes only a split second longer.

I would think it would make more sense to be polite and genuine.

Store clerk: "Hi, can I help you find something?"
Customer: "Thanks - does this come in red?"

I'm not saying I don't respond "fine, thanks" when someone I don't know and will never see again asks how I am. I am saying I find it just fluff because the person really doesn't want a response, and I don't really want to give one either. I simply prefer to keep business transactions as business. Polite, but not pretending it is a social interaction.