Be thankful that these scenes don't have pictures attached to them. Unless it's on the cover...
Duumvirate has one particularly memorable scene in which the inside of a vagina is likened to a hole in a brick wall lined with sandpaper.
The episode in Jim Butcher's ''Turn Coat'', in which Lara Raith, a White Court vampire (a gorgeous species which a. feeds on emotions and souls and b. enslaves the victim while doing so) feeds on her cousin Madeline Raith. Since Raiths feed by having sex with their victims, this should be an opportunity for hot girl-on-girl action, right? Wrong. Lara has been burned nearly to death in a battle. Being a vampire, she survives, but it takes all of her energy to do so, and she's ravenous afterwards. She rips Madeline's intestines out in a parody of foreplayThis is what ends up having sex with, feeding on and mutilating Madeline.
Hell, most White Court vampires are walking Fan Disservice. Jim Butcher really does not shy away from the fact that manipulating another person's sexual desire is tantamount to drugging someone to rape them.
Crops up in the book River God, set in Ancient Egypt: at the beginning of the novel, the thirty-five year old Taita admits in his narration that he's somewhat taken with the 14-year-old Lostris, his mistress. She's in love with 20-year-old Tanus. Despite this being fairly routine for Ancient Egypt, the book goes into numerous descriptions of Lostris' "red moon rising", and the fact that she spends much of the first part of the book half-naked does little to improve matters. After she's married to the Pharaoh, Taita, hoping to make her first night of sex with the king go without pain, is forced to rub ointment into the particularly important areas... Then there's the most disturbing part; Taita is a eunuch, and the castration is graphically described. Not to mention in one of the sequels Lostris is delighted to be pregnant, but her followers are dubious because it should not be possible, and unfortunately they are right; it turns out to be a tumor. And then in yet another of the sequels, Taita (now an old, old man) comes across an orphaned girl who had been raised by a village of tribal natives and who turns out to be the reincarnation of Lostris. He raises her, then they fall in love, but it only really works out after Taita regrows his missing member and gets the body of a young man after the finale.
Pretty much everything by Clive Barker of Literature/Hellraiser fame. (You think the movies were disturbing? Be thankful some things are hard to duplicate with special effects.)
Neil Gaiman has a good one in Keepsakes & Treasures about a character Mr. Smith who at first glance comes across as a heroic sociopath (with an emphasis on the sociopath) but nevertheless a cool and stylish sociopath. At one point he goes to visit a prostitute with whom he has a friendly relationship, and it's only revealed at the end that she is a young child.
In Anansi Boys at one point, a bony and less than attractive fifty-something woman drops her pants and waggles her arse as a distraction for the man who's locked her and her daughter in the basement. It's pretty clearly meant for laughs. It wouldn't be so funny if we had to actually look at it, though.
The whole Damane concept was supposed to be this in The Wheel of Time; For those not in the know: Any mage who gets a Damane collar put on her becomes enslaved to the woman holding the leash. The leashholder can not only feel every emotion from the mage, but also force the mage to feel whatever the holder wants. The Fetish Fuel potential should be apparent. It never comes up- the leashes are horrible, will-breaking, and the sense control is only used for agonizing torture. Nearly all of the Damane have had their collars for years, and are so completely broken that they won't run away if it's removed.
The first book of the Otherland series by Tad Williams has a scene in Mr. Jingo's, a sort of virtual-reality nightclub that's marketed towards teenagers and highly exclusive; it's actually a front the villain uses to collect the teens he's putting into comas to keep Otherland running. Williams apparently wanted to make it clear that this place is evil, and wanted to do so in a way that would not be Fetish Fuel to many, so he describes a virtual stripper removing her outer layers of skin and flesh and leaving the stage trailing body parts like the train of a wedding dress. Brain Bleach needed yet? Also worth mentioning is the way he portrays Dread's serial murders—Dread himself compares them to sex, and the narrative tone reflects that, but it's also fairly clear that we're supposed to be repulsed and consider him a monster.
Cissie in Montmorency is very pretty from the back with a hat on, but the front is slightly less pleasing. She is also a nasty lady. Later on, she makes herself pretty, but is nastier for it.
Norman Mailer's Ancient Evenings, a thousand-page "historical novel" about magic, sex and death in ancient Egypt, contains "more than enough bumbuggery and humbuggery" (in Howard Bloom's words) to "satisfy" anyone, and was described as difficult and unpleasant by William S. Burroughs.
The Anno Dracula books are set in an alternate universe where vampirism in Europe is a social reality, even fashionable. Naturally, a segment of society pops up to fill the needs of the new vampire population— so you get warm prostitutes selling their blood. It's played as utterly un-sensual, compared to more traditional vampire relations— streetwalkers with their throats and breasts covered in scabs, and mothers whoring out their children to vampiric pedophiles. Later, in Dracula Cha Cha Cha, you start to get waiters and waitresses being bled through tap-like devices stuck in their arms. Squicky? You bet. (Also in Dracula Cha Cha Cha, a zaftig vampire, Malenka, gets... larger, very fast, shortly after splashing in the Trevi Fountain. Her dress rips off. Then her skin.)
Juni Swan of The Demonata. She comes back from the dead wearing no clothes. The catch? She's now horribly mutilated and rotting to the point of chunks of flesh coming off when she moves.
While they were never originally intended for public readership, James Joyce's erotic letters to Nora Barnacle are now infamous for this. ThisHark! A Vagrant comic says it all.
Widely present in Andrew Vachss's Burke books whenever child sex is in the picture. The scenes are couched in terms that make it clear being aroused by them marks you as a freak who deserves a visit from Burke and co.
Sherman Alexie once wrote a short story called "The Sin Eaters", in which as far as fans can tell, there's a plague, and only full-blooded Indians are immune. Fine so far. The protagonist is a twelve-year-old boy. Fine. The Indians are placed in underground concentration camps. Fine for dystopian work. The Indians are forced to breed. Getting there. The protagonist is one of those forced to breed. Ew. The protagonist says she smells like his mother. ABANDON SHIP! ABANDON SHIP!
When the characters are in college in Wicked, there is some discussion of a mysterious "philosophy club." Eventually, it turns out that the philosophy club is actually a bar where people take drugs and are ordered to engage in bizarre sex acts, including sex between humans and semi-anthropomorphic animals.
Gregory Maguire has a habit of this. Case in point: Mirror, Mirror. Bianca wakes up, realizes she's grown up while she was sleeping, and then wham. Menstrual blood fountain.
A child in The Impossible Bird prayed to God to see a naked lady. An elderly neighbor forgot to close the blinds before changing her clothes. All he has to say of the experience is "It looked like an armpit."
The titular character dies during sex after handcuffing his wife to the bed; the rest of the book is her trying to escape while, among other things, a stray dog enters the room and begins feeding on her dead husband's body. This is one of the less disturbing things that happens.
It: A gang-bang orgy — involving the pre-pubescent protaganists.
In the Ciaphas Cain books, the psyker Rakel has a skewed sense of modesty and often wears clothes too tight or not properly put on. Problem is, she's not all there in the head even at the best of times.
Aliss, an Alice's Adventures in Wonderland rewrite, features multiple graphic sex scenes, some involving the title character. Just about every scene has something appalling, criminal, or just plain Squick-inducing, whether it be impassioned lovemaking in the midst of a tortured man's entrails, an S&M encounter that leaves a man lying on the street without any teeth, or a pedophile finally giving in to his long-suppressed desires.
Lady, during her time as a lieutenant to The Black Company is always described as being beautiful beyond words. She has a nude scene in the sixth book—where she is filthy and half-starved from weeks of campaigning, as well as being several months pregnant.