Knowing your audience is extremely important for Young Adult authors. When I read young adult partial manuscripts I first think is it something I enjoy (since I could be considered at the highest tip of the young adult audience) and then I think is it something I would want my younger siblings to read (who are at the bottom and mid-range of the young adult audience) and if they would enjoy it.
Unfortunately, I find the content in the young adult partials inconsistent. Either I like it, but would cringe if I saw my younger siblings read it or overall the partial is too childish. For example a character may be described as thirteen but swears like a sailor, or a fifteen-year-old character is acting more like a two-year-old (who wants read a main character having a tantrum?). If your character is thirteen, have them be thirteen not a thirty-year-old with a mature cursing vocabulary. Curse words don’t have to be added randomly into a young adult novel to make it be current or relatable. A character using curse words randomly seems like the author is trying too hard to be hip. Curse words are tricky because they can work well. If they are consistently (but not overly) used with the character being drawn, then curse words work well in creating a YA novel for all ages.
So again I want to encourage young adult authors to stop and think about whether the actions of your characters are plausible and can reach the wide YA audience effectively.