Don't worry! Just reply: 'Nie shi laowai' for the laugh out of the Chinese.

why do you ask? were you busy singling out a tourist, but couldn't fathom his defensive reaction? ever heard of body language? it reveals your intentions even if the "laowai" cant understand you. yes, really. imagine that…

EDITED. Some will some won't.

I watched tourists, they seemed not to want to talk or have anything to do with anyone, I guess they are suspicious of everyone. I doubt short time tourist would know any Chinese words. They are probably stunned watching the circus and often mumbling ''dumass''

Maybe, tourists have a biased view of China, they see fancy cars and shiny new skyscrapers then immediately think that China is heading toward more freedom and wealth for everyone, they couldn't be further from the truth. Tourists in Guangzhou (for e.g. because that's my city) mostly go to the beautiful, clean, orderly, glamor Tianhe CBD and Shamian Island, they see the nice places, they rarely see the crappy, dirty, old, "concreted to hell", messy districts of Yuexiu and Luwan with their beggars and street children.

Every countries have dirty places but in China it's more than 95% of the country where tourists rarely go, and the Chinese government or whoever else is in charge of tourism is very skilled at showing a completely false picture of its country.

Also tourists don't exchange with locals, the language and cultural gap is too large, Americans for e.g. have no problem to approach people in Europe, the opposite is also true, but in China it's another story, especially when locals see you as a walking ATM.

Why would they care?