I've been working with a natural language conversational agent for the last few months, creating a simulated personality from a novel, as a promotion for the novel. Natural language opens up a huge host of unreasonable expectations from the user, but more interesting is the utter gibberish people enter thinking they are conversing. When I say utter gibberish, that is exactly what people enter: sentence fragments with no subject, no verb and no correct spellings outside of "a", even "the" is most often spelled "teh". I suspect "natural language" makes people relax, but even when we hook in ASR (automated speech recognition) to get away from the gibberish spellings, the "sentences" people enter do not make sense. To some degree, I believe people are testing the limits of the natural language and knowledge base backing it, but too many of the "conversations" reveal an expectation of unreal super knowledge, like "you should know what I'm hinting, even though I can't spell or describe it"