Nabokov does a surprisingly great job of taking dark subject matter and making it entertaining. Pedophiles and molesters are one thing Americans have not come desensitized to. I remember going on a hot date in high school to go see The Hills Have Eyes. There is a rape scene and I could not even watch the whole thing. I felt sick to my stomach. Why then, while reading a book about equally disgusting subject matter, did I never have such a strong reaction? As mentioned by others, I can see the reason behind Nabokov's "Readings for Writers". We are not supposed to read within the constraints of society, we are supposed to just read without passing judgment. While the act of rape or molestation is inherently horrifying (not just a societal ideal/learned amount of horrifying), the way Nabokov wrote it made the subject matter seem less so.
While reading, I thought the book was both funny and tragic. Humbert's plight was not about pedophile once he started being with Lolita. He was a scorned lover. Like Lolita seducing Humbert, she ran the shots. His obsession gave him the lower hand. He seemed to be the tortured one, while she was good at manipulation. My sympathy was with Humbert.