I don’t actually understand the secret recipe thing, unless you’re a restaurant.
But it bothers me less than people who, when asked for a recipe, say, “Oh, yes, of course!” and then accidentally-on-purpose forget for the next millenia to get it to you. Just tell me you don’t give it out! I promise not to cry.
I get asked for recipes all the time, and I’m always willing to fork them over. I’ve found that pretty often, people don’t bother making the stuff, or they make it and it doesn’t taste quite right to them, and they end up thinking I’m an even better cook than I am. (No, I do not leave ingredients or steps out. I’m not that mean.)
On preview, I understand what you’re saying, Mangetout. I make something that my grandmother used to make, and the recipe includes milk measured by the half-eggshell and “as much flour as you need.” That one, if people ask, I tell them that it’s not written down anywhere and I’d really just have to have you over for the day and have a lesson.