Jane Austen's ghoulish sisters....

I admire Jane Austen and her works, but she does create in the modern mind an image of an early 19th century England full of sense and decorum. This even with sensibility contrasted with sense, and Lydia in Pride and Prejudice to demonstrate how wild young ladies could be, not to mention the outrageous behaviour of many real people of the time.

Of course, in Northanger Abbey she spoofed the "horrid" novels of her time, but that proves she read the novels, and we shouldn't forget just how popular they were. People of all kinds were eagerly gobbling up the gothic novels.

Foreign settings perhaps made the extreme believable.

Koenigsmark the Robber; or, the Terror ofBohemia: In Which Is Included, theAffecting History of Rosenberg and Adelaide

The Cavern of Horrors; or, Miseries of Miranda: A Neapolitan Tale

Included in foreign, of course, was Catholicism with monks, nuns, and convents, always fertile ground for the horrid imagination.

The Bleeding Nun of the Castle of Lindenberg.

The Convent of St. Michael or the Unfortunate Emilia

Father Innocent, Abbot of the Capuchins; or the Crimes of Cloisters

The Midnight Assassin: Or, Confession of the Monk Rinaldi; Containing a Complete History of His Diabolical Machinations and Unparalleled Ferocity

Then there are the novels about sex:

Conscience; or, the Bridal Night: A Tragedy, in Five Acts

The Southern Tower; or, Conjugal Sacrifice and Retribution

Much more can be learned about the popular reading of the time here.
http://www.cf.ac.uk/encap/corvey/articles