The streets all smell like piss and walking at night means seeing tons of rats.
The subways are absolutely disgusting and there's always a car that reeks of shit (you can tell because that car will have far fewer people than the surrounding cars).
I don't know if New Yorkers have never visited any other cities, or if they're just so blind from all the NYC-exceptionalism (Ayy if you can make it in New York, you can make it anywhere!!!) but that city is disgusting.