One thing that has taken some getting used to in Shenzhen - Spitting. It seems to be even more prevalent here than in other cities I've visited. So much so it seems expected to expectorate. I'm sitting at the top of a "mountain" just a little way away from my apartment and it sounds like the dugout of a major league baseball team (that would be like the Yankees to all of you people in Kansas City). It just goes to show you, you can take the person from the farm, but ....
My guess is that this horking habit still exists because just a generation ago or so, Shenzhen was a sleepy backwater, rural village with not many people and almost no modern buildings. However, in the past twenty-five to thirty years, the government of China decided (as only they can do) to create a modern city in Southern China to be a rival to Hong Kong. So now Shenzhen is a good-sized city (about 17 million people) with modern skyscrapers and more under construction all the time. The average age in the city seems to be in the low-thirties, which is amazingly young when you consider China's one-child law. I think I've only met one person during my trip here who is actually from Shenzhen; everyone else is a transplant whose huoko is in a different province, town or village where their family home is located. And how that relates to spitting? My theory is that these folks came largely from rural villages to urbanize and brought their local habits with them. And with so many of them here, fallen fresh from the tofu truck, it's hack-spit-hack-spit all the way down Nanhai Avenue. Not that I'm not accustomed to this. My neighbors where I grew up could spit many different substances (baccy, seeds, etc) with the best of them ... the main difference is the way the population makes an exponential difference. I grew up outside of a town of 300 people and we had about eight neighbors within a square mile. If you spit in a timber and no one is around to hear it ... not the case in this city.
So come on over, enjoy the culture of the city and spit where you please. At least they haven't brought some of baseball's other onerous customers.