On the face, not exactly a ringing endorsement.
In fact, that's the sort of comment that could make one's heart sink deeper than the Titanic (sorry, folks, but in honor of the anniversary I had to make the analogy...). And this remark came on top of a recent struggle to craft a query letter, some less-than-helpful criticism, and general angst about the publish-ability of my novels that I'm sure every writer experiences at some point. All of the above added up to a fit of blue-devils, followed by a personal examination of the nature of darkness.
"Dark" is one of those terms that everybody in publishing, film, and TV uses without really having a solid definition. To some, "dark" means "magic" (read, "satanism"); to others, it means "humorous in a tragic or morbid way;" and to still others it means "violent" or in some cases actually dark as in "dimly lit." I've used the term to describe my books, and at other times I've left it out as unhelpful or simply confusing (or worse, trendy).
At first I was disappointed in my Dearest Darling's reaction, but as I questioned him further he said, "I just don't like evil characters." My Dearest Darling found himself unsettled by the darkness of the human soul. He doesn't like the antagonist in my WIP, and I think by extension he doesn't like that part of me that enabled me to create a narcissistic, merciless, sadistic killer whose only real motivation is anger.
So, in other words what I've done is to create a character that feels disturbingly real. He's a nightmare from the deepest recesses of our imagination come to life on the page, a waking horror. He's frightening, the more so because a living breathing person assembled him word by word.
But, dare I mention that we're not supposed to like evil? That we're supposed to be frightened of it, and look for some way or someone to combat it? Because there's evil in the world and on the page, we need heroes. And, lest anyone think I've succumbed to my own darkness, I'm also the creator of the protagonist who ultimately defeats the villain. And my hero's light is mine, too.