I can understand changing knickers that have got damp or otherwise unpleasant... but mostly I change clothes if they smell, or I think they will, which means specially in hot weather. But in winter I may wear the same T shirt for days. (around the house, not to visit the queen). It'd just never occur to me to think 'Oh no, there may be a bacterium in it!' As far as I'm concerned, if you can't see something's dirty then it isn't. I think I'm agreeing here with those people who said we're far too finicky about 'germs' these days; it seems to me it's no coincidence that things like asthma are so much mroe prevalent among young people than they used to be.