If you can be accused of having intended to deceive it counts as a lie in most social functions. If you can't be, as in changes of subject or not answering the question, that counts as good manners. It can be infuriating to the questioner if you are less subtle than you think you are, but only really upsets fairly rare people. With those rare people though, it may be a better idea to just admit that you aren't willing to answer or to place a condition on answering. We have had conflicts over this in the past where you would have done better by doing so in any event.