Cincinatti, Ohio! ... possibly my belief is linked to an experience I HAD there one dark night on my return from the 'Wild West' to NY.
Having a few hours to put off before my next connection was due, I decided (somewhat unwisely, perhaps) to roam around the - by stark comparison with Las Vegas - dimly~lit side streets adjacent to the bus terminal.
Suddenly ... I was confronted by what can only be described as a "ghostly" apparition! And all I could see were ... what appeared to be whites of the eyes ... and a set of equally-white teeth grinning at me from a shop doorway ... !
... well ... the "apparition" turned out to be nothing more than a (probably harmless) lone bystander, loiterer ... whatever ... of Afro-American origins. Nonetheless, it was scary at the time and, despite being a BIG bloke, I deemed it prudent to beat a hasty retreat ... ... discretion being the better part of valour!