...then don't buy Big Brother.
It's set in contemporary Liverpool, FFS!
Now I am a working-class 'lady' who was born and brought up in Liverpool, and from my early teens I have to admit that I swore. I swear still, especially when I'm pissed off, and even now I get a bollickin' from my old mum for doing it (she's eighty-five, four foot nothing, and will flatten you if you start any trouble with her. One thing she doesn't condone, though, is bad language, especially from a girl! :D)
I also hold a degree which makes me professional class. So what? I still know my swear words.
So, I'm afraid, do kids these days. There's no getting away from bad language in the street or in the playground, so why can't it be reflected in young adult literature? Well, when people see the 'f' word written down, it shocks. It shocks me when I hear it on the telly, but I still use it in every day life.
There isn't a single young reader out there, whatever class, who hasn't thought if not said the words 'Oh, shit!' when something in their lives has gone tits up.
My characters in Big Brother live on a run-down council estate, and their lives are crap. In the real world when your life is crap your only release sometimes is to swear about it. Swearing in YA literature won't influence how a reader thinks today; they already think it. What it does is it reflects what's already happening in real life.
Times have changed. Young people's literature has changed. We're not talking Jennings or Just William here, we're talking Big Brother, and he's a bastard you don't wanna mess with. End of.