depends how they look at it. It could just be that your average zhou has only met foreign teachers. So especially if they see a young guy not wearing a suit or obvious business attire they'll just assume.

second could be wishful thinking for them. theyre insecure about themselves/their country so they see a western person and want a reason to look down at them.

Elevators are fun places.

I live on the 37th floor so it takes a good 25-30 secs to get up here. One evening when headed back home I walked in the entry hall and there was this couple near the elevator, I shook my head out of common politeness, they were talking about the laowai (obviously me) and how he is a teacher, blah blah all the usual bullshit about foreign teachers. I had a crooked smile when hearing them but didn't say anything.

As we walked into the elevator my phone rang, it was my partner (and friend) with who I am co-running our recruitment agency. We had a quick chat in Mandarin on professional topics that were clearly not what teachers would talk about regardless of what school/center they work at.

The couple immediately got that 1. I am not a teacher and 2. I understood what they were saying. I saw them again and they did not talk about me anymore thinking that I tingbudong, ever.