I usually prefer not to show when I fold. Keeping opponents guessing is part of the game, and even showing a bluff can give away information about how I think. The only time I might show is in a friendly home game for fun or if there's a specific psychological reason to do it against a particular opponent. In the long run, I think giving away less information is usually the better strategy.
You can choose to reveal just one card, or you can ignore that option and reveal it later in a situation that suits you. Psychology and mindset play a major role here, too: you might want to sell a bluff to your opponent so that, next time, they won't believe you and will end up calling when you actually hold the nuts.
