Well, for starters, I don't. But it occurred to me that my moustache is likely a place where a lot of things accumulate, for example, wax, food, dribbles from the nose, and anything else that might happen to land on my whiskers. But I find if I shampoo my 'stache it becomes very unruly and it takes quite a bit of wax to tame the beast. Okay...when I shower some water runs through it, but there are no fingers or soap involved. Every morning after I shower and shave I comb my 'stache and lay in some wax and style it to the desired shape. I don't shampoo or make any particular effort to wash it...unless of course, on the odd occasion, I've eaten something that was particularly messy (e.g double cheeseburger with the works including bacon, and several sauces) and the only way to get it out is to rinse my 'stache under the tap. I find often a fine tooth comb will remove any crusty bits. Maybe i'm overthinking this, but is it really necessary to wash your moustache? Opinions welcomed. And if you do what is your process?