The most disturbing part I think is the fact that it's a true story.
You mean Lolita? It's not a true story. Humbert Humbert and his prison remembrances are all just fabrication. But, yeah, sure, the theme is questionable. Though come on! Dominique Swain in the 97 version was just wonderful in that cringe-worthy way. Neither movie is really a classic, despite 1962's Kubrick-Sellers collaboration. The book isn't a classic, either. Sshh. The only reason it stands out is because it's OMG fucks a 12 year old! in the 50's. It would hardly be shocking today, and Nabokov wouldn't be able to hold a candle to anyone.
Classics are tough, though. It's easy to pull the Casablanca's out of the hat but, really, we all know it's Big Trouble in Little China and Carpenter's remake of The Thing.
Red Dawn. Princess Bride. The first Die Hard. Star Trek II. KHHHAAAANNN!!!
Oh, and, Chinatown. And Murder, My Sweet with Dick Powell in as Marlowe. He outshines Bogart's Marlow by miles, and both the book and the movie are direct inspiration for the Max Payne dream sequences which almost ruined that game.
Strangers on a Train, North by Northwest...
Oh, well, there are far too many classics.