Vietnamese weasel coffee aka Kopi Luwak is not my idea of quality beans, LOL. I have seen a lot of it in my travels (regular coffee not Kopi) and it depends on the beans. When I am in the east the cheap beans are Robusta and I believe they are from Vietnam. They always smell and taste very acidic and lack the qualities I am used to.
They do produce a lot of coffee though so I would suspect that they are probably one of the larger producers. Aside from that there are some blends that I get when I am on the road from SB that claim they have beans out of that area. It tastes ok, and I am sure that they have better grades of beans.
I am partial to South America though and my favorite is Kona, so take my opinion with a grain of salt.