In Chinese culture, which traditionally places a high value on education, self-cultivation, and social harmony, being 粗俗 (cūsú) is a significant character flaw. It is the direct antithesis of 文雅 (wényǎ), the quality of being elegant, cultured, and refined. Confucian values emphasize 礼 (lǐ), or propriety and proper conduct. Actions or words that are 粗俗 are seen as a violation of 礼, reflecting poorly not just on the individual, but also on their family and upbringing. This can cause everyone involved to “lose face” (面子, miànzi). To an American or Western learner, 粗俗 is very similar to “vulgar” or “crude.” However, the cultural weight can be heavier in a Chinese context. While a Westerner might call a raunchy comedian “crude” as a simple description of their style, describing a person as 粗俗 in a Chinese social setting is a much more direct and serious judgment of their entire character and social standing. It's less about a specific action and more about a fundamental lack of personal cultivation.
粗俗 is almost always used in a negative and critical way. It's a common term for judging behavior, speech, and aesthetics that fall short of social expectations.
It is a formal and strong criticism. You would rarely, if ever, use it jokingly unless you know someone very well, as it can easily be taken as a serious insult.