I always wonder what the disinfect-everything people do when they visit friends. Do they refuse to sit on the couch in case the upholstery hasn't been cleaned? Do they wipe down the bathroom before using it? Do they rewash all of the plates and glasses? Or do they just cross-examine their friends to make sure that everything has been cleaned up to their standards?

FWIW, as a budget traveller I've done quite a number of homestays, bedding down on peoples' spare beds and using their kitchens and bathrooms. Other than the normal handwashing and showering, I have no particular sanitizing regime, and yet I'm seldom ill at home or on the road. By far the worst infectious disease I've ever had was an antibiotic-resistant bug that I got while in the hospital for a broken bone.