Yes, it's true up to a point. Too much soaking will actually leach moisture out of the skin, like a dishwasher can end up with dry, chapped hands. That's why you don't want to soak unless it's necessary. By "two hydrometers", I am guessing you mean two analog (not digital) hygrometers, which are often extremely inaccurate. If you can replace them with a digital one or at least check them against a digital hygrometer, you'll have a much better idea of the actual humidity.