Chinese will scam you for anything, if they feel you are a sucker and they can get away with it. But to be fair, it's not just the foreigners who are targets. Chinese tourists from other regions are also considered fair game by enterprising locals. It's just that cultural and communications issues can't be blamed there, so the level of scammer competency has to go up when trying to fool another Chinese. It's pretty frequent, though.

And yes, never, never, NEVER, Never confirm you want any product or service unless you have ascertained price, and (if you are not a decent Mandarin speaker/comprehender) have it written down with paper kept with you in case of later shenanigans with the bill.

FWIW, the most egregious attempt at scamming me ever played by a restaurant, was not in China but at Rome's Piazza Navona. They didn't get away with it. They got their bill re-added correctly with the exact amount due + coperto (idiots didn't realize I write down prices of what I'm ordering as I go, and always carry a calculator).