I've been both to Hell, MI and Hell, Grand Cayman. Neither were "Hell on Earth", quite the opposite.

I haven't done much international travel (Lagos, Dominican Republic, etc) so my nomination for Hell on Earth would probably be Beaver Falls, PA. Actually Beaver County, PA would fit the bill except for a few spots.
Depressed area, truly part of the "rust belt".
When it snows I don't remember once when the snow was truly white. It was always a dirty grey color. Probably from the numerous incinerators.
Closed down steel mills and people standing on town corners just being unemployed. Depressing. Generational Depression is an interesting topic to study in this area.

Although I have to include as a caveat, that this area is not the worst of all areas as I met mrs. infinityplusone here, before she was mrs. infinityplusone
(Fortunately, neither of us called this place home for more than a couple years).