I always find this a hard topic to deal with because, personally I'm not offended by things. Worst case it's a picture of something really gross I didn't want to see so I grimace and scroll past it... and it's gotta be pretty extreme for that reaction.
As a kid, my parents didn't allow swearing so I learned not to... at home or around adults/strangers. When I'm in a comfortable setting around the right people, I'll have the nastiest jokes and the most colorful language. I can turn it on/off like a switch... and since some people find swearing offensive that's an important skill to have. The thing is both as a child and still now at the age of 34 I don't think it means anything, they're only words. We're now discussing having kids and I think about this stuff and realize 2 things...
1. I don't believe swearing is a big deal or even important.
2. Some people do and the kid is going to need to at least turn it off around grandparents and such.
So that's what I'm going to have to tell them. "Look, I know it's just a word but some people get really upset about it. Just keep a lid on it for their sake."
You can see that discussion right here, there are clearly those of us who just don't care and a few people who care a lot. I can't personally wrap my head around why a word- any word or pictures of naked or nearly naked people gets some folks so upset but I can clearly see that it does so just to be nice I gotta know when to shut it off. The trick there, of course, for we unoffendables is knowing where the line is and since it's different for everyone that's a really hard thing to find sometimes.
This ties in to how I see how raising kids should be. Kids need to learn to respect others and to not cause others distress/harm/irritation. Whether it's avoiding the f-word around grandma or not being loud at a restaurant or just being generally considerate of others around them that is the most important thing. If they want to swear and tell sick jokes with their friends, who cares as long as they know when to shut it off.