Sometimes there is more than one "correct" method. In a lot of those cases, the "wrong" way is pretty specific, or at least tightly constrained. At such times,

Sometimes there is more than one "correct" method. In a lot of those cases, the "wrong" way is pretty specific, or at least tightly constrained. At such times, it is easier to explain that instead of explaining a large group of extremely different options. Other times, it is just a simple case of "I don't know what works, but I know what doesn't work". This allows the next person to not make that mistake.