From Jo Walton at Tor.com comes the idea of The Suck Fairy, that scourge of re-reading that somehow curdles fondly remembered books upon second reading. Working alongside the Suck Fairy are her siblings the Racism Fairy, the Sexism Fairy, and the Homophobia Fairy, according to Walton.
One might add the Bad Writing Fairy; sometimes re-reading fondly remembered pulp adventures from my junior high school years (I'm looking at you, Doc Savage) highlights the sheer awfulness of the prose.