I was debating the washing thing with a friend a few days ago: he maintained they wore clean linen, rather than washing the body, because of a fear of water-borne disease - I live in a house with no central heating or - as of 2 weeks ago - hot running water, and I think it's because, unless you were happy to sit in a tub in front of a ground floor fireplace while some unfortunate person filled and heated dozens of kettles from a pump or well, it's a lot easier to just put on a clean shirt!