What are the bad habits in ancient and modern times?

Eating wild animals, littering, dumping garbage and sewage, spitting everywhere, coughing and sneezing without covering your mouth and nose, smoking in public places, littering, defecating, dirty toilets, especially squatting in the garden in rural areas, fortune telling, feudal superstition, ignoring environmental hygiene and family hygiene.

Heterogeneity of ancient marriage in China: Yin marriage is related to "ghosts"

Yin marriage, also called ghost marriage, is to find a spouse for the dead. Some boys and girls died for some reason after they got engaged, but they didn't wait until they got married. At that time, the old people thought that if they didn't get married for them, their ghosts would do mischief and make the family uneasy. So we must hold a wedding for them, and finally bury them together, become husband and wife, and be buried with their bones. In case there are solitary graves in the fields of men and women.

Foot-binding is a bad habit in ancient China.

The bad habit of "worshipping the door" in ancient officialdom