This afternoon a man is coming to measure up my living room for a new carpet... so I have hoovered the current one to within an inch of its life... but why?  The whole point is it's going to be replaced...

Next week I have a dental appointment so my teeth will be brushed, flossed and generally made gorgeous... but why?  The whole point is the hygienist will do a scale and polish...

So why do we do it?  Doctors, dentists, opticians, hairdresser, carpet fitters, electricians, plumbers... why do they reduce sane adults to a frenzy of cleaning and tidying?