A couple of months ago, I was reading over SPARK, making some final edits to it. I hadn't read it in its entirety since last fall. There were a few scenes I came to that made my face heat up and caused me to giggle like a thirteen-year-old. I had forgotten how . . . umm . . . steamy some of the scenes were. I actually started to wonder if I should tone them down to make them less offensive, but then I realized, those scenes are vital to the storyline. I have to show my characters walking that dangerous, fine line and their temptation to cross it. Changing those scenes would've compromised my story.
I don't think anyone should write for the purpose of offending (seriously, is there anything worse than a book/movie where the f-bomb gets gratuitously thrown around for shock value?), but I also don't think you should write worrying you might. If what you write doesn't offend someone, then it's probably not worth reading. OUCH! Harsh words, eh? The truth is, no one wants to read fluff.
The young adult genre is always "offending" people. Cheerleaders get mad, because they get portrayed as snobs. The goth community gets mad, because they're portrayed as freaks. Atheists hate books about angels, Christians hate books about demons, and blah, blah, blah. My point is, everyone is different; no matter what you write, there's no telling how people will perceive it. Write what feels real to you, and don't worry about offending people. The worst that can happen is you get people talking, and that's not always a bad thing.