I do use strong language in my books but they are very definitely not written for YA. I think that YA books are all the richer for the exclusion of bad language. See Jonathan Maberry as a fine example
Swearing seems to be part of everyday conversation in a lot of teens today. But i still think authors should be careful about how much bad language they include in their work. I don’t think they should just add it in to make the story more inviting to the reader. Even some young people find swearing or explicit language offensive or embarrassing. It should only be used if it is necessary to the story and not just for sensationalism.