I think research goes along way! Meeting them in person (consultation) . I've been lucky with all my artist because I've got some really nice tattoos. All these tattooers know each other and love to see great tattoos. You have to look at it like everyone has days where they aren't feeling 100 percent friendly and just want to give you a tattoo. That's what matters at the end. Unless they are completely arrogant and an ass that is another story. Being that you're in China you have to understand the cultural thing.
One of my saying is "if you don't like it don't eat it'