When I was in college, I went to a nail place owned by a Vietnamese family, and got to be really good friends with one of the guys that worked there. He told me that they do talk about customers sometimes, but that it could be complimentary or not, depending on the person and the situation. So, I guess that if you don't speak the language at the shop that you go to, you may never know exactly what is being said. I guess that you have to deal with it, or go to another place.