Real, hardcore S&M erotica in the vein of books like Sadopaideia, A Man and A Maid, the novels of F.E.Campbell, and even the outright porn of the "Bizarre Library" series seems to have entirely died in today's market.
What we have is either BDSM "lifestyle" and Ds stories or "Erotica", basically bodice rippers with more sexual detail.
After going blind searching the bookstores and Internet for anything to suite my taste, I was driven to write my own. Stories with real, well researched plots and characters, but enough S&M action to work as stroke fiction if that's what the reader wants (needs?).
I'm a successful professional, so I know what the "real world" is like. I'm widely traveled and multilingual. I do nude photography and CGI art, so I know what naked women actually look like, and I have wielded a whip and used it on (willing) women from all over the world.
If you too are looking for something harder than just sexed up romance, take a look at my books. Note that NONE of my books fall under the category of "Erotic Romance".
And if you are looking for some interesting SF/Horror have a look at the book "Vampire-Tech" which is by me too.