This may or may not be news to you, but hairstylists like it dirty. (It being your hair, you saucy little minx.) While there's something to be said for squeaky clean, aromatic, and you-can-run-a-brush-through-it clean hair, we prefer ours a little greased up. And thankfully, the cool-girl hairstyles of this season practically demand it. From messy waves to edgy slicks, these looks are reason enough not to bother with a shower.