Thank you for your reply. We aren't a new listing--we've had 6 apartments on Airbnb for 2 1/2 years with over 100 reviews, which makes it especially strange that they would target us. They do appear to be from China, and when I see their first question, I know they are a scam. But I'm still polite just in case they're real.
I'm happy to hear that the only way they could achieve their scam is for me to contact them outside of the app. I never talk to people outside of Airbnb app, and have had several ask to come see the property first, etc. Just --no.