So does the Amentan collection of hygiene practices actually produce cleaner public areas and than similarly-developed Earth societies? And does this translate into lower rates of infectious disease, or does the crowding cancel it out so they get sick about as often as 1st-world humans?
They have cleaner public areas - they keep them cleaner in the first place (Amentans never spit gum onto the sidewalk or pee in places they shouldn’t; they might decline to run after a blown-away napkin but do not litter deliberately), they make them out of more-cleanable surfaces (if it can’t be effectively scrubbed it can probably at least be pressure-washed; permanently-stainable grout between pretty tiles is undesirable), and because they clean more (fallen leaves, dust and grit, stray napkins, etc. are cleared away regularly). They have somewhat lower rates of infectious diseases, but less because of that and more because it’s unthinkable to go to work sick etc., and this is compensated for somewhat with the crowding and the heavy use of public transit. Their diseases probably tend to have longer contagious incubation periods where they can’t notice they’re sick because that’s the way the pressure would run.