China makes:
Mexico look clean.
the Middle East look clean.
India look clean.
China wins the filthy award...the muddy crap award.
The first impression I remember from China is observing a cleaning lady in a restaurant cleaning tables with the mop she just used on the floor. And it was in the bathroom before that.
India is by far filthier though.
Middle East is very different regarding sanitation standards.
In Egypt it is a rule not to eat out unless in a good hotel or any western run establishment. The same applies to India.