Sorry I phrased that weird, I am not quite too sure what I am talking about either!I personally do not know what you are referring to, I am assuming ''the difficult questions you cannot prepare for'' and I would just choose an answer that best suit the situation and makes sense for obtaining the best result in the situation.
I am referring to curveball questions like "how many credit cards are there in the UK", "should the PM travel in a driverless car" etc.