Yeah, I'm with Fenrix on this, any time I've read erotic for erotic sake anything it is usually awful, not just in plot but in the writing and editing suffering because they aren't the point. But when it makes sense in a story, particularly when it fits thematically/emotionally then it can help.
Honestly, most of the authors people are going to bring up (Laura K. Hamilton for one) are authors I have a problem with from a writing craft point of view. I don't like them because of how they write, and can't really get more than a few chapters into things. And then some of the examples mentioned take it to another level. I react to 50 Shades of Grey and Twilight like a vampire to holy water. So no, I haven't read the whole things, but I've read a chapter or two and been absolutely floored that writing like that could get published. And I've watched the first Twilight movie with RiffTrax so I know the plot more or less. Um...Line?
In many cases, I think eroticism works better than actual sex. Dracula would be a prime example of this. Ramsey Campbell has a collection of erotic horror called Scared Stiff. It isn't his best work, but it is interesting and pretty good. But the biggest criticism you could make about it is that a lot of his actual sex scenes are... not good. In that collection I think it works okay because none of them are meant to actually be erotic, so the lack of it isn't as off-putting, they are meant to be off-putting. But in some of his novels, oh Yig, the man cannot write sex scenes.
Clive Barker can go either way for a lot of people, I'm not really a fan of the sex in his writing, but he does the erotic lead-up well, and this often contributes to the horror. Poppy Z. Brite is an excellent writer who does a good job with the sex scenes.
