Sometimes I just don't get it.
I participate in several author-oriented forums on Reddit and Facebook. I do my best to provide helpful feedback and information, even brief critiques when time and inclination permit. One common post seen in these groups is from newer authors who ask why their books aren't selling. Once I have a URL to the Amazon page, I review the book's description (i.e., blurb) and use the "Look Inside" feature to scan the interior pages.
Sometimes, I see little that actually needs to be fixed, which means the problem is generally related to ineffective marketing. Remember Field of Dreams and its premise that "if you build it, they will come." Publishing isn't like that. If you write and publish it, readers won't necessarily come. They won't be aware your book exists. Awareness requires marketing. Effective marketing requires sustained effort and a strategic marketing plan.
Don't ask me how to go about that, because marketing is not my forte.
Three things, however, will enhance your book's chances of selling regardless of the level of marketing which an author employs:
Content littered with errors, weak and/or confusing writing, inconsistencies, plot holes, etc. leaves a bad taste in readers' mouths. They'll take note that a particular author produces poor quality stories and refuse to purchase from said author again. Poorly written and poorly edited content build an author's reputation for sloppiness and carelessness.
A book that's well-written, well-edited, well-formatted, and has a great cover and still isn't selling generally has problems other than quality. Sometimes the problem relates to miscategorization, or the wrong keywords for SEO, or ineffective (sometimes nonexistent) marketing.
That said, when an author solicits feedback as to why his or her book isn't selling, I will delve into the book and report on what I find that the author can and should fix. I offer some specific feedback: an amateurish cover, formatting that doesn't meet industry standards, a lackluster blurb, and a host of flaws in the content that merit a professional editor's attention. Such solictations often garner similar feedback from at last a dozen people, many of them professional editors and commercially successful authors—people who know what they're talking about.
So, why doesn't the author asking for that feedback make the suggested corrections? I'm not griping about an author not hiring me to edit a deeply flaws manuscript, but an author's failure to implement the corrective actions that will fix the book's flaws and improve its chances for success.
I don't get it. Asking for suggestions for improvement should lead to making the suggested improvements. When they don't, the request seems to me an disingenuous attempt to get people to purchase the book without actually asking people to buy the book.