<<Disclaimer: Verify this information before applying it to your situation.>>
 
I have been particularly motivated to find GF chinese food in chinese
restaurants - I have just moved to Hong Kong to live. I have been to both
averagely-priced and expensive restaurants in this cosmopolitan city - always
with local people and my personal experience is ..
 
- expensive restaurants more motivated to help with special requests
- MSG widely and consistently used in less expensive restaurants (even in rice
  and steamed food). This is more of a problem than soya sauce.
- some foods (eg duck) injected with gluten-containing mixtures to improve
  taste/look/etc
- do not assume that waiters pass on requests (or even understand them) to the
  kitchen staff
 
On the positive side, somebody typed out the Cantonese characters for a
'message to the chef' for me which I can show in restaurants. I have a
restaurant guide for Hong Kong which has a MSG usage (yes/no) entry
for each one (not just the chinese restaurants).
 
Unfortunately, I am going to focus on non-chinese restaurants when I can as
there is always the risk of contamination, even with specially-prepared
meals.
 
Regards .. Margaret Doyle