Officially, haircuts and street markets aren't supposed to have dual pricing and you can refuse to pay the higher price. Any attempt to charge foreigners more depends on how gullible the foreign customers are.
Vietnam has unofficial dual pricing at many tourist restaurants and tour programs as well. However, officially, dual pricing is limited to a small number of tourist sites. The only one I can think of right now which still charges foreigners more than locals is the Hue imperial palace. Elsewhere, it's what the locals think they can get away with (experienced this once at a Phu Quoc seafood restaurant, where ironically, I was present with a group of Thais as well as my father, a Chinese lady and a Vietnamese friend). Thanks to him, the restaurant didn't succeed in ripping us off, but probably would have if he hadn't been present.
I was referring more to "official" dual pricing, which mainly applies at tourist sites including national parks (for 2.5 months beginning in mid December and ending February 29 this year, foreigners could actually enter a select number of national parks for free (once only for each park), while Thais paid the normal entrance fee). Perhaps later this year, they'll do the promotion again. Museums, temples and even marathon entrance fees are higher for foreigners.
Malaysia does the same at many tourist attractions.
China used to practice dual pricing until 20 or 25 years ago, but now the only possible exemptions to the uniform pricing policy would be for locals who live in the town/city/district where the attraction is located. Otherwise, Chinese people from anywhere else in the country and foreigners pay the same.