Genuinely interested here...
I go to a Chinese nail salon, and two of the staff (a man and a woman) continually make that snooking noise like when you're trying to swallow phlegm.
It's such a disgusting noise, and turns my stomach but neither of them seem to have any self awareness and just snook away quite happily!
They wear masks, but I wondered if it might be down to something they're breathing in inadvertently during the course of their work. But I cant fathom how they think it's OK? Is it normal in Chinese culture?