(germs can't live in a dry environment for that long) .
This is not always true. Hepatitis viruses and encapsulated bacteria can live for days or years on surfaces. But of course he cleans and disinfects, so problem solved.
[End public health service announcement.]
As to the "think they know it all" types, my advice as a therapist is smile and nod. You know they're full of "it" even if they don't.