I think the problem is that "Young Adult" encompasses a wide level of maturity, and authors may tailor their works towards vastly different levels of maturity, that the quality can vary quite a bit. Some works are targeted for young readers, but are rather mature in their execution (well explained, well reasoned character motivations and plot, etc), while others bank on the possibly lower expectations of the young and inexperienced reader. I've picked up some horrendous young adult fiction before and read it (I'm looking at you, James Patterson!). That doesn't keep me from reading it, but it does make me wary...