You would be surprised by Against nature. Sensuality is sweating all through the pages. And the promise of some sexual fantasies also happen. Probably the most sexual book I have ever read. That's maybe why Lord Wotton recommended this poisonous book to Dorian Gray. During his trial for deprivacy, Wilde was repetedly blamed for quoting such an indecent author.
"His eye fell on the yellow book that Lord Henry had sent him. What was it, he wondered. He went towards the little, pearl-coloured octagonal stand that had always looked to him like the work of some strange Egyptian bees that wrought in silver, and taking up the volume, flung himself into an arm-chair and began to turn over the leaves. After a few minutes he became absorbed. It was the strangest book that he had ever read. It seemed to him that in exquisite raiment, and to the delicate sound of flutes, the sins of the world were passing in dumb show before him. Things that he had dimly dreamed of were suddenly made real to him. Things of which he had never dreamed were gradually revealed.
It was a novel without a plot and with only one character, being, indeed, simply a psychological study of a certain young Parisian who spent his life trying to realise in the nineteenth century all the passions and modes of thought that belonged to every century except his own, and to sum up, as it were, in himself the various moods through which the world-spirit had ever passed, loving for their mere artificiality those renunciations that men have unwisely called virtue, as much as those natural rebellions that wise men still call sin. The style in which it was written was that curious jewelled style, vivid and obscure at once, full of argot and of archaisms, of technical expressions and of elaborate paraphrases, that characterises the work of some of the finest artists of the French school of Symbolistes. There were in it metaphors as monstrous as orchids and as subtle in colour. The life of the senses was described in the terms of mystical philosophy. One hardly knew at times whether one was reading the spiritual ecstasies of some mediaeval saint or the morbid confessions of a modern sinner. It was a poisonous book. The heavy odour of incense seemed to cling about its pages and to trouble the brain. The mere cadence of the sentences, the subtle monotony of their music, so full as it was of complex refrains and movements elaborately repeated, produced in the mind of the lad, as he passed from chapter to chapter, a form of reverie, a malady of dreaming, that made him unconscious of the falling day and creeping shadows."
Hence, this decadency is not pornography. This is not Venus in furs. You have to read between the lines...