It’s always disappointing to see cooking myths repeated by people who should be skeptical enough to know better. Partly it’s worrisome because it makes me wonder which fictions I believe.

The biggest myth in cooking is the one about searing meat. You know, “searing meat seals in the juices.” This is totally, provably false, and Harold McGee devotes an entire chapter to disproving it in multiple ways in his great book The Curious Cook. But you still hear it all the time–even in recently published books, and even in so-called science books like Hillman’s New Kitchen Science.

There’s probably no harm done if people go on believing that searing meat makes it juicier, because there are good reasons to sear meat anyway: it makes a flavorful and attractive crust, just one that happens to be entirely permeable to liquid.

Other kitchen myths have unfortunate consequences. The one I’ve heard in the past week from two otherwise trustworthy sources is that you should never wash mushrooms because–the epithet is always the same–“they’re like little sponges.”

It’s true that mushrooms are like little sponges. But they’re already saturated with water. Think about what happens when you put mushrooms into a hot pan: they release so much water that they shrink to a fraction of their size, right? A fungus so waterlogged is in no position to take up more water.

You can prove it with a simple experiment, one McGee and Cook’s Illustrated both did in print years ago. Take some mushrooms and a kitchen scale. Weigh the mushrooms dry. Soak the mushrooms in water for as long as you like. Drain. Weigh again. They will have gained a fraction of an ounce, all of it in surface water. How can you prove it’s surface water? Repeat the experiment with something obviously non-absorbent, like rocks or broccoli, or the brain of whoever told you mushrooms soak up water.

Who cares? Well, if you believe that mushrooms and water don’t mix, you’ll painstakingly wash each mushroom with a brush or (not too) damp cloth. Dinnertime will come and go and you will still be there washing mushrooms. Your friends will nickname you “shroomie” or something else that suggests that you have a drug habit. If you know the truth, you will rinse your mushrooms under running water, or–for the delicious but very dirty wild mushrooms that start showing up this time of year–wash them in a bowl with several changes of water.

Okay, I admit it: if I’m just cooking a few mushrooms, I’ll still wipe them. Once they’re wet, they get slippery and tend to escape across the cutting board. Come back, shroomie!