I don't mean lying about qualifications, or lying about jobs you've had in the past. But, I feel no compunction about answering a question like "tell me about a time when you had a conflict with a colleague" by making up a scenario that could plausibly have happened and hypothesizing about what you might do in it. The reality is that no two such scenarios are ever exactly the same, so a real anecdote would not be helpful, even if you happen to have a good one in mind (which I never do). Next time, the people involved (including you) are going to be different, with different personalities, a different set of problems and pressures and constraints . Forget it, there's very low predictive power in a question like that, even if the interviewer were qualified to analyze you. So, just tell them what they want to hear, and prove you speak the dumb language of corporate interviews.
Is this unethical? Maybe, but only to the extent that such questions are meaningful filters (which I believe they aren't). And it is surely no more unethical than answering a question like "why do you want to work for Company X?" by saying "I am inspired by the mission and the fascinating problems you're solving" rather than "the salary is higher than my current job, and I think it will make a good stepping stone to an even bigger salary at another company in a few years", which is what we would say if genuine honesty were what that particular discourse was trying to get at.