Have you been to China? The tier 1 cities like Beijing and Shanghai are positively manicured compared to the average US city (or Paris, for that matter).

Of course it's a huge country and it's not too hard to find an open-air market with meat hanging on hooks or public lavatories that you wouldn't want to enter without a hazmat suit, but people emptying their night soil out the window into the street below is not really a thing anymore.

In my travels to about 8~9 cities in China, I don't recall seeing anything that was dirtier than, say, Amsterdam or New York or Busan. Not having lived in Medieval Europe, I can't say exactly how dirty it was, but saying China is that dirty seems like an exaggeration.

This is the exact discrimination/mindset that @quicklime is talking about. Have you ever been to China?

But those dogs are probably far healthier than they were in the past. You don't fear rabies if one of them bites you. You aren't going to get a parasite if you pet them.