Thanks to Ellie for taking the discussion to an even deeper level by mentioning Michael O'Brien, whose book, A Landscape with Dragons, is exceptional. In it, he shows that the problem with much of the modern fantasy genre is that it turns the moral universe upside down. Characters that were once, and always, evil, are now imbued with good and noble traits. His example is the dragon. Once historically and biblically the epitome of evil -- the dragon is now cast as savior. In the case of Eclipse, the vampire, traditionally an evil character, is cast as good.
It's as if the authors of such fiction want to numb their readers to the idea that real evil exists and is consistently recognizable. If you're convinced a dragon, or vampire, can only be deemed bad after you've gotten to know him, you're more likely to give all the dragons and vampires a chance to prove their character before making a judgment. Sadly, the time that passes between meeting a new and as yet unjudged dragon/vampire and deciding whether he's of the good sort, or bad, is a time of extreme vulnerability.
This is problematic because we know there is a dragon, Satan, who's goal is to devour what's good, all the while "masquerading as an angel of light." In the world we inhabit, even a dragon that appears good is evil. O'Brien writes, "Evils that appear good are far more destructive in the long run than those that appear with horns, fangs, and drooling green saliva."
Hat tip: Joe Carter