The worst ever public toilet I ever saw was in Sakai, Osaka, Japan.
My host family and I went down to play some football at a park near their house, and the youngest son in the family dared me to go look at the toilet there (or at least I think he did, I don't speak Japanese very well, and he didn't speak English very well
). So I walked over, host family giggling behind me, and a the first thing that tipped me off that I was about to see something terrible was the horrid buzzing sound the small outhouse was making.
Slowly I opened the door, unleashing the millions of flies that had made their home inside (at this point my host family was rolling on the ground laughing, including the ridiculously clean and polite grandmother). But the flies weren't the worst of it, not by a long shot. It was a western style toilet, that looked like some one had taking to it with a sledgehammer, cracking one side clean off. What remained of the bowl was awash in feces and maggots. The breaking of the toilet bowl must have been quite powerful as the walls and ceiling were splattered in all manner of horrible things.
On top of the cistern was a
very large hentai magazine, whose pages had been torn up and plastered over the walls, not in some haphazard way, but in a way that you'd imagine a serial killers bedroom would look. The elder son in the family drew my attention to the rubbish bin out side the toilet, filled from top to bottom with hentai magazines, soiled tissues, and the real kicker, a large, dead, partially burnt rat sitting on top.
I was thankful to return home, to the magic that is the normal household Japanese toilet, heated seat and all.