To kill a mockingbird: Horribly boring, and the plot never seemed to go anywhere. It was less entertaining than reading a documentary on racism in the early part of the twentieth century, and more pretentious.
Harry Potter: they may have been good compared to most children's books, but were illogical, full of plot holes, and just plain STUPID when compared on any adult level. Why I read all seven of them I have not the faintest idea.
The Giver: or, as I like to call it, "Baby's first dystopia."
Animal farm, which, while being a good enough metaphor for the soviet union, disturbed me so much as a child when I read it, that I wrote a fanfic where all the characters die in a nuclear strike.
Fahrenheit 451: yes, it made important points at first, but when it degenerated into essentially a rant about television making people stupid, it pissed me off so much that I actually thought the ending was an appropriate coda.
Plato's Republic: Hitler aint got nothing on Socrates!