Maybe the real problem here is people constantly asking each other how they are, even when they don't know each other and will never see each other again (grocery store cashier, etc.). Does anyone ever expect anything other than a short, positive answer? Is this a silly American thing, or does it happen elsewhere, too? The whole exchange is just a waste of time, so while I think answers like a sarcastic "living the dream" are stupid, I can understand a person's desire to say something, anything, that's different from "Fine, how are you?" Seems like we could just say hello and leave it at that, or move on to more interesting conversation.