Well…mildly profane ones. Especially “damn”, “damned”, or “damn it!”.
Until the early 1970’s, I believe you could never say such words on US television (except in some religious contexts). Also, when Clark Gable said “Frankly my dear, I don’t give a damn” as Rhett Butler in Gone With The Wind, the producers were fined $5,000 dollars! That pretty much kept the word out of American films for another 20 or so years.
Also, at least at the elementary level, our teachers didn’t let us use those words either. And in some older books I’ll even see “d—ed” or “h—” in print.
I suppose both might be slightly strong words due to their religious meaning - but so many other like words weren’t censored. Since Shakespeare surely used such words with impunity (“Out, out damned spot”), I imagine that it was a later set of attitudes that caused these words to become "dirty
". Is it a puritan legacy? Did Queen Victoria faint at the mention of Hell? Did or do British people get so fussy over such words (Aussies sure don’t seem to care), or is this an entirely AMerican problem?