My tastes as a reader are a lot more varied than my tastes as a writer. I love reading the horror and fantasy stories authors such as Stephen King and Jim Butcher write, but I would never want or attempt to write one. As far as erotic romances go, I'm willing to read stories that actually "squick" me out. I could never write them, but I have to admire the creativity of the author whose characters make me squirm in my seat.
So, premise comes first. Does the story blurb or tag line intirgue me enough for me to spend a few hours with these characters? I'm fairly new to reading BDSM, but I was quick to discover what I did and didn't like in stories that take you beyond vanilla.
Personal choice, I avoid books that contain:
1.) Menages. Yeah, I know they're popular, and some of the stories that contain MMF (male, male, female) or MFM or FMF can be really great books, but I don't like heroes and heroines who share. Sharing your beloved is just not romantic to me. The sex can be hot and the prose electric, but I'm too busy shaking my head as I read it to enjoy the story.
2.) Exhibitionism. Once my hero and heroine become involved neither one of them would ever insist their partner walk around before others without any clothes on. In some books, BDSM especially, these are power plays by the hero. He likes to see her naked, so he wants others to enjoy looking at what he possess. Yeah, okay. I can understand he's proud of her, but does he really want others to staring at the naked body of the woman he loves or wants to be with on a more serious basis? What about possessiveness? Even a hero who espouses a "look, but don't touch" philosophy doesn't do it for me, and if he actually lets others touch and fondle her.... Well, why bother having anything special with him if he's so willing to share?
3.) Sadism. I have a problem with heroes, or male protagonists, who actually enjoy causing the heroine pain. I want him to protect and care for her, not take pleasure in injuring her. So, given my attitude on that, why do I let my heroes spank?
My paranormal heroes tend to use spanking as a promise and a threat, however, they also need to make sure the heroine believes they will make the threat a painful reality if pushed. For me, and this is a personal thing, barbed words and the cold treatment are crueler forms of punishment than a firm smack on the butt. I don't mind the hero and heroine arguing, but walking out on each other is not a solution in my mind. Nothing gets resolved that way. However, if the hero has given his beloved several warnings, and she's still not paying attention, taking her over his knee can be a great way for him to get her to at least listen to, if not actually see, his point of view. She may be, and often is, angrier than a hornet at his high-handed attitude, but to avoid further punishment she'll quickly calm down and listen to what he has to say. More often than not, he is making a very good point, since his usual reason for punishing her in that manner is because her conduct puts her in danger of hurting herself. And once she concedes to his greater wisdom (from his point of view), he is also more than eager to prove just how much he cares about and loves her.
So, to sum up, I like stories where the hero and heroine are committed and protective of each other. I like the hero to be a dominant alpha, which means he's usually a little over-controlling (a trait he often needs to curb) and tends to tread on the chauvinist side of political correctness. The heroine is most likely stubborn and more than a little feisty. She loves him despite his faults and isn't out to change him as much as she is into broadening his perspective.