Book Misdescriptions - why is female agency over emaphasized in blurbs?

I read a lot of samples. I read samples of books that look like they might be femdom. I read samples of books where the blurb suggests that they might have a really awesome strong heroine who knows what she wants and isn't afraid to ask for it. Much of the time (most?) I'm wrong. The book or novella might sound promising, but it usually becomes quickly obvious that it's not even subtle femdom.

The disjoint between the book description and the actual book is not unusual, I know. Romances are famous for having titles/covers/descriptions which bear no resemblance to the story inside, especially in the lines of Greek billionaires and virgins. But let's look at an example, because I think the disparity is more important here than the normal hair color and ethnicity mistakes that are typical in romance novels/descriptions. There are plenty of books which say they have strong heroines, but she's actually weak and TSTL. But this also happens in BDSM books - women are represented in the blurb as being more dominant than they are in the book. For instance, here is the description for The Breaker's Concubine by Ann Mayburn:

Prince Devnar of Jensia is goaded into raiding the wrong space ship, springing a trap that captures him for use as a Royal pleasure slave, a Concubine, on Kyrimia. He vows to do everything he can to escape and keep from forming a psychic bond with his captors that would render him absolutely and totally in love. This proves difficult to do when  the female Breaker assigned to turn him into a Concubine, Melania, is the epitome of his perfect woman.

Melania has been raised and trained to help reluctant and abused Novices to break through their personal blocks and attain the ultimate prize of becoming a Concubine. When she is given Devnar to train, she finds herself in danger of doing the forbidden and falling in love with her Novice. This angry, scarred, and utterly seductive male tests her self-control like no other.

Devnar and Melania find themselves at the heart of a galaxy wide political battle that will test a love that they must not acknowledge, and cannot live without, to its very limits.

Very early on the heroine thinks about how she likes to relax by being submissive and the book continues along these lines. But the cover, with the hero in a collar, cuffs and submissive pose does nothing to dispel the notion gathered from the blurb that this is essentially a book about a man submitting to a woman, rather than vice versa. I think that this is essentially the same issue as the strong heroine one - it's an over-representation of female agency (in this case dominance rather than strength and intelligence) in the description.  

This is a philosophical as well as a practical problem. In a practical sense, it's frustrating that books I think I will enjoy turn out not to be what they were represented as. But philosophically, I think there is a wider problem: blurbs represent women as being strong, in control and having agency, but the book itself frequently has a weak, silly TSTL girl. I think there are several potential reasons for this.

• Readers want strong women, but authors haven't gotten with the program yet, and so the publishers represent the heroine as being different from how she really is.
• Readers think that they want strong female characters, but actually like stupid and or submissive female characters. 
• The publisher and author genuinely believe that women behaving stupidly and or submissively is a strong heroine. 

The difference between the first reason and the second is how satisfied readers are with the book after they have read it. This is a difficult thing to judge. Instinctively, reviews seem like a good way to assess readers satisfaction. But, as I've already said, I read an lot of samples and decide that the book is not for me. I don't write reviews of these books, so my annoyance at the disjoint between book description and content isn't represented on review sites etc.

It's also possible that readers want their heroines to be idiots and 'strong' or 'feisty' is a shorthand for that, rather like 'virgin' is shorthand for 'nice'. Worse still is the idea that maybe people genuinely believe that in a woman, TSTL = strong. The really worrying thing to me is the idea that this disjoint could be propagating the idea that heroines who are TSTL are actually strong and independent.

I really hope that publishers and authors will realize that book descriptions really matter - and that books described as having strong heroines can actually have strong heroines.

What have been your experiences with book misdescriptions? Why do you think that female agency is over emphasized in book descriptions and under delivered in the book itself?