I doubt if Clark Kent/Superman ever say a profanity.
No way No how?
No so sure about Bruce Wayne/Batman.
But if they happen to do it.
Blame it on the minds of thirties something comic book writers.

Steve Englehart, Roy Thomas, Marv Wolfman/*** Wein/Deny O'Neil
was all able to avoid the language.

Sure, they could and these were the minds that build upon the characters of Stan Lee/Jack Kirby and hosts of other creative minds.
But then it's the sign of the times.
When respect just not in the mindsets of present folks.

Containment is a foreign language to writers today.
Who put in thoughts of heroes things they wanted to say.
What next?
Aunt May cuss or curse out Peter Parker.

Don't doubt it?
We dealing with the minds of comic book writers.