re: Filthiest cities you've visited

In the US, it has to be New Orleans. I did not find NY to be all that filthy though like any big city it has undesirable parts. Haven't been to Detroit, Akron or Cleveland.

All that said, New Orleans is basically a sewer.

Internationally, I found that Seoul, while very interesting, was filthy. People in the US who complain about filth and pollution really have no idea just how clean we really are.