All I can say is that if you have any Speedy Wok-type restaurants in your area, do NOT sit by the swinging kitchen door as you wait to receive your to-go order.
Along with Speedy Woks and swinging doors, any one making a habit of eating in all those fashionable, exotic places that serve raw fud, finger fud, sloppy, drippy un-pronounceable mixtures of stuff raised in a chicken poop fed pond, is a great candidate for taking an occasional stick of ivermectin. It will clean them right out and probly solve the occasional mysterious problem they’ve been having?