[theorique]

They also call swearing "unprofessional", as if that's a bad thing. Again, it suggests a laid back atmosphere, where no-one cares if you swear when you're dealing with a particularly nasty bug.

Swearing at work, I don't find particularly unprofessional. I've worked (and currently work) in environments which rival pirate ships for off-color jokes and profanity.

However, these same workplaces never put swearing in a job ad. To me, that would be kind of a red flag. In the spoken case, it's an ephemeral, off-the-record kind of thing. In the written case, in an official HR document no less, it's quite different. Frankly, I'm not sure how profanity would make it into an official job posting.

Of course, it's a very different matter if you're emailing your college buddy to ask him to come work for your awesome company, but then this would not be a job ad for public consumption, would it?