Swearing doesn’t necessarily indicate a lack of intelligence or integrity. It’s just an emotional expression, rather than an intellectual expression. Some of the most intellectual, well-educated, and pious (including monastic) people I’ve ever met often swear in private.
Many society scale things — such as definitions of beauty and intelligence, technologies, languages, laws, narrative plot structures, etc. — apparently evolve through a process called “structuration.” Basically, trends emerge from small-scale to large-scale; then companies, governments, and the like incorporate the trends into their policies or products, which they impose on the masses; the masses (ab)use those policies or products in certain ways, the patterns of which emerge again into large-scale trends; the powers-that-be modify their policies and products; and the cycle repeats. The cycle also could start with something that is initially imposed by companies, governments, or the like (e.g., some breakthrough technology, or the designs of currencies or ID documents).
The back-and-forth between individuals and societies apparently even affects people’s genetics. Though many of the physical differences between ethnic groups are environmental adaptations (e.g., dark skin is more protective against UV radiation, which people in sunnier places need, and light skin is more efficient at producing vitamin D, which people in darker places need), features without much utilitarian value (e.g., the arched noses of many people from the Mediterranean to South Asia, the pointy facial features of many northern Europeans, many East Asian women’s straighter figures, etc.) may be the way they are because those societies have long considered those features to be desirable/beautiful. So, over many generations, people with those features in those societies might have had an easier time finding desire/reproduction-oriented relationships. This anecdotally seems true on dating websites; people who their society probably would consider especially beautiful often seem to have had children as young adults.