Foul words have entered everyday vocabulary, with today's grandmothers using the very words (or worse) for which she originally washed out her own child's mouth with soap as a mother only 3 decades ago.
This can be true in parts of modern frum society too sometimes.
Foul English words have also entered Israeli Hebrew as slang (because they don't know what they're actually saying & because cussing in a foreign language doesn't have the same jolt). Even some frum Israelis end up using this vulgar English as slang within their modern Hebrew.
However, Judaism insists not only on non-vulgar language, but on refined language in general.
When asked about lashon nekiyah - clean language or a clean tongue - Rav Avigdor Miller mentioned the words mothers traditionally forbade their children.
Then he goes a step deeper and discusses refined language in general - "mindful speech," if you will.
For example, he explains, in Slabodka where he learned, they never said the word shlecht, which is Yiddish for "bad."
They never said the word shlecht. Never. I was there six years. Six years – and they never said the word shlecht. “Not good,” they would say. But they never said shlecht. They never referred to a goy as a “sheigetz.”
Because that’s a Sheketz. The word “sheigetz” comes from the word sheketz a disgusting creature. “Sheigetz” is sheketz. But a goy is not a sheketz. He’s a tzelem Elokim...
The word “sheigetz” is never found in Slabodka language.
So, in a good environment, if you make sure to stay in stay in a good environment, you’ll pick up what is called lashon nekiyah.