In Chinese culture, 黑 (hēi) carries a powerful and often negative symbolic weight, deeply connected to the concept of Yin and Yang (阴阳). Black corresponds to Yin (阴), which represents darkness, cold, negativity, and the underworld. This is a primary reason why the character extends to so many negative concepts. Traditionally, it's also a color associated with mourning, though white (白, bái) is more prominent in this role.
Comparison to Western Culture: The connection between “black” and “illegal/evil” is very similar to English. We have “black market,” “blacklist,” and “blackmail.” However, the Chinese usage is arguably more direct and widespread. For instance, calling the mafia 黑社会 (hēishèhuì), or “black society,” is a much more literal and common term than any English equivalent.
There is a fascinating exception in Chinese opera, where a character with a black-painted face, like the famous Judge Bao (包拯), symbolizes impartiality, integrity, and fierceness. In this specific context, black represents a stern and incorruptible authority, a stark contrast to its usual connotations.