Xeque,
You've obviously never flown on a proper First Class (BA, CX, QF, etc.). You are provided with a "sleep suit" into which you can change and your clothes are put on hangers in a wardrobe while you sleep (in the case of the better airlines under a nice comfy duvet). It's also perfectly possible to have a shave before landing (2 toilets between 8-14 pax is enough)