I don't have experiences with PRC or vietnamese brides or
friends who have married them, but i share something that is
relevant.
I shoot weddings regularly, and last month, had the pleasure of
going to KL to cover a wedding there. quite an elaborate affiar,
the couple was affluent, and i suspect so were their friends.
The moment i started in the morning, i was greeted by a cheerful
"jie mei" who was preparing the tekan stuff for the groom. soon, a
few more joined in and started chatting with me asking me for
suggestions and what i thought of their evil plans. spoke perfect
english, confident, looks wise ok, nothing to complain about,
fun-loving, uninhibited and DEFINITELY NOT dao. can u imagine the
same of a singaporean girl, educated overseas, affluent,
good-looking? wat's the chances they will come up and initiate
friendly banter with you, esp if you're an ugly wedding
photographer "intruding" into their fun? 
I contrast that to singaporean weddings i shoot. sure singaporeans
girls are not total OPPOSITE, but it does take them a while to warm
up. some never do, mind you, and snuff you all the way. there's
something about singaporean girls being dressed up and looking
pretty (in their opinions entirely) that they have the right to
snuff any stranger.
i'm sure i have treaded on many (female) toes here. just sharing an
experience, and generalising. don't come and reply me saying, eh
not all sg girls are like that, i know alot of malaysian girls so
this that and the other. 
maybe that KL wedding i shot was a very RARE case. let's see if i
get the chance to shoot in KL more often. 