Showing your cards is a tactical act. Showing after everyone else folds needs tos erve a purpose. If it doesn't, it is giving away information needlessly. I only show to achoeve specific results. For example, if I'm trying to convince people that I am a straight arrow and non-bluffer, I might show a nutty hand at an appropriate time. If I have won via a bluff and I want to put someone on tilt, I might show them the bluff they just caved in against. But genreally, the stakes/levels I play at, it is just not helpful to give away this free information.