This is not a subject I think about often, mostly because I’ve already made up my mind about it. In addition, the decision to use or not use swear words in writing seems incredibly minor and nitpicky in comparison to some of the weightier decisions a writer has to make on a daily basis.
Nonetheless, I know plenty of people who dislike swearing, whether it is expressed aloud or in writing. And I know that some writers are hesitant to include swear words in their writing for fear of offending their readers, so I’d thought I’d give my two cents on the matter here.
I do use swear words, both in real life and in my writing. When used correctly, swear words have a powerful effect that no other word can achieve. “What the hell?” is a lot more effective than its milder cousin, “What the heck?” If a swear word would work better than a euphemism, then by all means, use it, even if it ruffles a few feathers. Trust me when I say that readers who are bothered by a little swearing are not worth having, anyway, as they are usually the same kind who rarely seem bothered by things like excessive violence, rape, torture, deception, or any other immoral subject you may write about that is much worse than a dirty four letter word.
This is not license to swear whenever you want. Constantly swearing is funny under certain circumstances, to be sure. And certainly, if one of your characters has a naturally dirty mouth, there is no problem with having that character swear more than others. After all, some people in real life swear more than others, so I see no problem with writing a potty-mouthed character.
The problem comes when you use swear words every other word for no reason other than pure shock value. By their nature, swear words need to be used sparingly. Think of swear words as salt. A little bit of salt can bring out the flavor in an otherwise bland meal, but too much can destroy what little taste your food may have had and make you quite sick in the process.
The same applies to swear words. Use them when necessary, but no more than that, otherwise you risk distracting your readers from your main point.
Of course, I suppose swearing is not appropriate for every audience. Young children’s books, for example, can usually do without even the mildest swearing, perhaps nothing worse than “heck” or “darn.” So you should keep your target audience in mind when deciding whether swear words are appropriate or not, although even then I don’t think you should sweat it too much because swear words really aren’t a big deal at all.