A) You can tell the food will be good in a place where all the staff is Chinese.
B)To hell with the staff, be they Chinese, Mexican, or Martian. The test is whether there are Chinese people -eating- there.
Best Chinese food place where I live has a totally (Hispanic/Latino) kitchen staff, and one guy who apparently speaks Spanish/Chinese/English... we all assume he gets paid nicely... or at least gets a lot of overtime. And Chinese people eat there.
A totally crappy Chinese food place where I used to live is all Chinese (Or all Asian, I suppose I really don't know). It's a buffet, so it's kindof a given that it wouldn't be that good... but it's really kinda crap. Cranky women who'd be trophy wives if they'd married up higher eat there.
People argue this point with me. Someone whose mother used to own a Chinese restaurant argues this point with me, but I seem to remember there was no logic to his reasoning.