I met 3 coders who swore more or less continuously while coding. But that's 3 out of probably close to 100 I have been sitting close enough during 30 years. I do it myself but probably less than at one hairy problem a week.

At least one of the 3 does not produce better code than average. One produces clearly more code than average. Not really bad code, but we are still fixing his bugs quite a while after he left the company. The 3rd one I don't remember, just shared an office, but did not work with his code.

Edit: To be clear I talked about swearing aloud. Having swear words in the code I have not seen with 30 years of experience. Except some rare examples in open source which get then a lot of publicity.