I just finished reading It Takes a Scandal by Caroline Linden. I found it very enjoyable, as I usually find her books. She doesn't usually trip up my suspension of disbelief, although I can't quite believe the trope about the serial erotic novel 50 Ways to Sin. Considering that Fanny Hill was banned shortly after its first publication and circulated afterward only in pirated copies sold illegally, it is highly unlikely that a series of erotic pamphlets would continue to be sold, even under the table, in reputable bookshops patronized by ladies of gentle birth.
Other than that, the story was engaging, the characters likeable, and no one was TSTL. The slightly villainous rival showed signs of redemption at the end, and he will obviously be the hero of a future novel. The resolution was a bit too neat and quick, and the hero must have rolled a +6 for healing, because about a day after he suffered a debilitating re-injury that left him barely able to walk, he managed to lift the heroine and carry her to his bed (at least he didn't carry her up the stairs; that would have strained belief way too much).
Although there was some heavy petting earlier in the story, the only full sex scene came near the end of the book. That has been a trend with many of the mainstream historical romances I have read in the past few years, even by those authors who used to include multiple sex scenes in their books.
I found a link to this USA Today article on Linden's Facebook page. It claims that, with the rise in popularity of erotic romance novels, even historical romances are getting hotter. Actually, I have found the reverse to be the case. I believe that the growth and marketing of erotic romance as a separate genre has led historical romance authors to reduce the amount of sex in their books in order to appeal to a different group of readers (and avoid being misclassified as erotic romance, which could limit their book's distribution, in the same way that an "X" rating keeps a movie out of mainstream theaters).
Caroline Linden has found a way to reach both mainstream historical romance readers and those who enjoy erotic romance (which often include threesomes and BDSM). She alludes to 50 Ways to Sin without actually including its racy scenes in her book. However, Avon offered the first few "issues" of the serial to readers who pre-ordered It Takes a Scandal or bought it within a week of release and sent proof of purchase via a link on their website. Readers of the USA Today article can also click a link to access one episode of 50 Ways to Sin (which will only be up until May 28, so hurry if you are curious).
The pamphlet-within-a-novel is quite definitely erotic and is clearly inspired by Fanny Hill. It also works as light parody of the erotic romance genre. Kudos to Caroline Linden for finding a way to spare the rod (or whip) and use it, too.