Be very careful when paying at restaurants and bars as most of them offer DCC (Dynamic Currency Conversion). When they do you can see on the ticket that you can pay in either HKD or the currency your credit card is issued in (USD in my case as it’s a US card).
Please keep the tickets and check your account a few days after. Too many times i was charged in USD even though I selected HKD on the ticket and that I also wrote the sum in HKD!!! DCC is infamous for taking outrageous fees out of the customer. Per my calculation on couple bills it’s between 4 and 5% they’re stealing from you!
Not sure if waiters are getting a commission from their employers pushing and cheating the customer like this because it’s happened to me too many times already