As bicycle attendant Guo Guiyou stands guard outside a busy Beijing railway station, he suddenly makes a loud coarse noise as he opens his mouth and propels a gobbet of spit on to the pavement.
"It's good to spit, it's good for your health," said the 40-year-old man unapologetically as he rubs his shoe over the foul puddle he has just created.
Although there is now a wide consensus that spitting is "uncivilized" behavior, as pre-Olympics manners campaigns term it, spitting is still pretty much a trademark sight and sound across the country.
Even though the government has stepped up punishment for spitting, a possible fine of 50 renminbi (US$7) does not deter Guo.
"That's okay - most of the time, they don't see you," he said.
Few who visit China can help but notice the frequency of spitting in public, which often follows a irritatingly gravelly clearing of the throat and lungs, and a complete lack of embarrassment about the habit.
Late paramount leader Deng Xiaoping (鄧小平) was a known to be an enthusiastic spitter who proudly kept a spittoon close by when he greeted foreign dignitaries at the Great Hall of the People in the 1970s and 1980s.
Although the practice spreads diseases that are rife in China, it is still common on the roads and alleys of the Chinese capital to have to dodge disgusting blobs of saliva - especially in winter when they freeze and become hazardous to pedestrians and cyclists alike.
But to many Chinese, spitting is a physical phenomenon as natural as sneezing or belching, and is traditionally nothing to be ashamed of.
"Well, I can't spit inside my car, can I?" said taxi driver Sui Ningguo, as he wound down the window and propelled his phlegm outwards. "No one cares about spitting anyway."
Medical experts say phlegm is generated normally when one is suffering from respiratory infections, but it is also produced when the lungs are irritated by pollution and habits such as smoking and eating heavy, oily food.
Li Yan, a respiratory disease expert at Beijing's Xuanwu Hospital, believes widespread respiratory infections, partly due to China's polluted environment, and the population's lack of hygiene awareness contribute to the habit.
"Dry climate in many Chinese cities, coupled with bad air quality, also lead to the build-up of mucus in one's respiratory tract, hence generating phlegm," she said.
She said air-borne respiratory diseases such as tuberculosis, pneumonia and influenza can be spread by the phlegm of a disease carrier.
Doctors say the urge to spit is probably more to do with the commonly perceived concept in China that one should spit whenever one feels a throat irritation.
"A lot of it is just bad habit. Some people spit even when there is no phlegm and what they spit out is in fact saliva," said Wang Jidong, professor at the Beijing Chinese Medicine University.
"But saliva is part of your normal secretion and aids digestion. It's just a wrong idea that people have."
Earlier this year, officials admitted that getting the capital's residents to bring their manners up to international standard in time for the Olympics next August could be a bigger task than constructing the new sports venues.
Zhang Faqiang, vice head of the Beijing Olympic organizing committee, said the most difficult area in staging a "civilized" Olympics" rests in "the quality of the people"