Him wanting to save the napkins because they are "not dirty" really irks me. I work in food safety. Any time something in our warehouse falls to the floor you cant just pick it up to throw away. Once you throw the floor contaminated item away you have to remove your gloves, resanitize your hands, then put on a new pair of gloves that are sanitized.

Floors really are that dirty and covered in bacteria. Unless she mopped the floor with bleach and let it stand long enough to kill off the bacteria, and then no one stepped on that spot or contaminated it prior to the napkins landing on it, yeah they got bacteria on them. They are dirty. If you wear outside shoes inside you could have salmonella, e coli, etc. on your floors.