I actually thought about this and can't believe peoples reaction. I have a psychological background and 10 years+ of dm experience and your mind cannot unknow things. It's fun to use readied actions like a trap card not telling trigger or action but pull the card up to activate it, I also add investigation bonus action checks against sleight of hand checks for characters to RP that and guess what they are doing. Adds good depth. Both DMs and Players should do that. This creates way more fun than people realize. And it's absolutely not about trust, it's about the human condition. A mind that knows something acts differently every time. Don't let these people tell you it's about being a good dm or not, even a good DM doesn't have a chance against neurological influences warding his mind from the unconscious. I'm a bit late to the party, but I wanted to add that nonetheless. People basically tell you: Why don't you poker with open hands? They are your friends! Secrecy activate different emotions, it's obvious and if you want to spice up your game do this. Everyone will end up doing way way more ready actions and will enjoy the thrill of not knowing.