I worked in after school care for four years, and then became a teacher. Now that I'm "retired" (no longer seeking employment) I work at my church's gift shop. All three of those professions prevent me from reading books with foul language.
If I read the words, they'll be tucked away in the back of my mind. Then, on the worst possible day, when I'm exhausted, hassled, and overworked, those words will pop out of my mouth when my guard is down. And, it will always happen at the worst possible moment, in front of the worst possible person. And then, I've got trouble.
So, the easiest solution is to just avoid reading or hearing the language to begin with.
Anyone who works with children or who provides a service to the public is in the same shoes. Foul language is offensive, and it just isn't permissible in a lot of situations. The easiest solution is to avoid hearing it, reading it or being exposed to it.
So, if you want to sell more books, choose your words carefully. If you don't absolutely have to use that word, then use a better one.