Originally Posted by
eng3
I'm not sure if I have "the look". I was in Singapore last year for work and eating dinner at the airport with a group where I was the only "asian-looking" one. All the staff seemed to be speaking Cantonese to each other. One of the waiters walked directly to me and asked me a question in Mandarin. I had wondered why he assumed that I spoke Mandarin. I had been speaking English to my co-workers the entire time. I assumed because Mandarin is more prevalent over there.
address Cantonese speaker in Mandarin --> Cantonese speaker either replies in Cantonese or speaks Mandarin in a way that will be obvious to both parties that they should switch to Mandarin
address Mandarin speaker in Cantonese --> Mandarin speaker may, especially in a touristy area, wonder why the staff are not being more accommodating to tourists.