Before he passed away a few years ago, I visited my 90-year-old great-uncle once a week in his assisted living apartment. He was at that stage of life where he didn't want to do anything but watch TV. Well, that and complain that no one ever visits him (which isn't true) or that he'd rather be living anywhere else but Texas (which probably isn't true either). His memory failed him often, and I know he got very frustrated over that fact.
One day, we disagreed over whether he was taking his medications correctly. He insisted that he might be old and grumpy -- he was right about that! -- but he knew exactly what he was doing with the medicines. I countered that, because he was taking the Sunday medicines on Tuesday, things might not be quite kosher. He informed me that I should just mind my business and he'd mind his. He used various curse words in his diatribe, and I finally left after I told him I'd come back when he was in a better mood ... and I didn't want to yell back at him. Being a respectful great-niece, I said that last part in my head, though.
So here's the tie-in to writing ... after listening to my great-uncle curse at me, I'm thinking about curse words and their effectiveness in dialogue. In several of my stories, the characters curse frequently. They even use words that I don't use in my speech. To me, though, the characters talk like that because they talk like that. It's a part of them, just like their eye colors or physique.
The question is this ... should I cut down on obscenities (and perhaps also sexual situations) or leave things in that seem inherent to the characters and their lives? I don't know that I have a firm answer. I believe in letting the characters tell their stories, but if everyone who reads the stories is terribly offended, have I done the characters an injustice? The answer might be that the characters aren't exactly real so I, as the writer, can make them do whatever I think is right.
However, I don't think anyone has told my characters they aren't real because, most days, they do whatever they darn well please. And sometimes they do whatever they damn well please.
P.S. My great-uncle was a very kind man who called me "Pumpkin" my entire life. But sometimes, as people age, they lose their filter. I never held the cursing against him because I think he was quite unaware he was doing it.