I can only speak for myself and my own experience, but the odds are very slim. The YA market is so diverse, and we can put “clean reads” like Shannon Hale’s Goose Girl beside
edgier work like Holly Black’s Tithe or M.J. Anderson’s Feed (both books that tell great stories but have some language content some might not want to read), and both kinds of books will be valued and enjoyed by their target audience. There are so many different kinds of teens and so many different kinds of readers that I think a good story will find its home.

Personally, I as an editor choose books for what’s IN them, not for what’s NOT in them. I want a good story. Thus, I can love Tithe and Feed and many books like them because they tell good stories. I feel the content that some might find objectionable is rarely gratuitous in YA (not so for some adult books I’ve read . . .)–it always supports the story. (For example, when you read Feed you feel like the characters’ use of degraded language directly illustrates how their culture has degraded.)*

A lot of people feel that “teens talk that way” and if you don’t include foul language it won’t feel real to teens. I know teens who talk this way and I know teens who don’t–just as I did growing up. I myself have never found a need to use a curse stronger than “darn,” but I have many friends who swear like sailors and want to see their own reality reflected to them in books as much as I do my own.

If you write a compelling story, no editor I know is going to make you add edgy content you don’t want, unless you’re trying to write an edgy story without edgy content and coming off corny. (Example: if your “bad” character swears a lot but the worst he ever says is “fiddlesticks,” there’s something wrong.) If your characterization and plot work, the story should work without adding anything extraneous. Your content should match the story you’re trying to tell.

Here at Mirrorstone we try to make sure our books–even our YAs–meet a self-imposed PG-13 rating. We don’t have any hard and fast rules that I have posted on my wall or anything, but we weigh every swear word, every scene with implied or overt sexual content, and scenes of extreme violence, and ask, “Does it serve the story? How can we tell this without disturbing our younger readers? Is this going too far?”  And then we edit accordingly. Usually it’s to tone down a scene already written, not to add content to a scene. 

For example, for an older middle grade novel I once edited, we had a fight scene that included decapitation. I weighed whether the violence was too graphic. I decided it was okay because the good guys were fighting off monsters and the monsters could only be killed by cutting off their heads (any other ki
nd of wound just temporarily slowed them down). It worked for that book and the author handled those fight scenes artfully.

My take on this: Write the book you want to write. Write a good story. If your story is one that doesn’t need that kind of content, it’s rare that someone would suggest it should.

Also . . .
As you go through the editing process, your editor will undoubtedly say many times, “It feels like a scene/paragraph/reaction is missing here . . .” She might suggest something, but usually she’ll leave it up to you to answer the questions she asks. 

But perhaps at some point an editor might suggest that the story should veer in a direction you don’t want to take it. Editors are here to suggest how to make the story better, and you never know, an editor might feel something you are opposed to is necessary for the particular story in question. 

If this rare occurrence ever happens to you, it’s nothing to be afraid of. Discuss it with your editor. Find out what she feels is missing, and then see if you can find another way to solve the problem the editor has identified. I know few editors who will say you MUST do this or I won’t publish your book (it has to be a BIG problem for that to happen after a contract has been signed). Both editors and authors must learn the art of negotiation, and of getting to the heart of what’s wrong in a story. I give suggestions as a way to spark ideas for the author. Suggestions rarely mean edicts.

*I must say, if you haven’t read these books because you don’t want to read bad language, you’re missing out on a good story. But then, I rarely watch rated R movies despite being told they’re a good story because I find that few balance out against the content that got them the rating, so I understand where the concern comes from. I can skim things as I’m reading that I can’t as easily when I’m watching something. (But I won’t give up Glory. Or, well, I have a soft spot in my heart for Terminator 2.)