I had a repairman here yesterday. He was working in the basement, and probably thought no one could hear him, but he was muttering F’s frequently. Didn’t inspire confidence.
So, as you say, that would not inspire confidence.
That said, Patton was a cusser. I don't think he cussed out of frustration. I think he probably cussed to emphasis the importance of what he was saying.
“Researchers found those with potty mouths are less likely to be associated with lying and deception.”
https://www.thesun.co.uk/news/2650769/people-who-frequently-swear-are-likely-to-be-more-honest/