The point is that you don't want to try to be like the locals. The locals in developing countries are not healthy and do suffer from poor sanitation (diarrhea alone is responsible for 8% of all deaths in Asia -- WHO stats). You need to be sensible and avoid certain things.

I just got back from a month in China and didn't get sick despite eating many things that'd make a typical westerner puke. I lived in China for several years previously and had learned the hard way about food safety.