The cover art for their book. You may hate it with a passion; you may think that it misrepresents both the plot and the theme of the book in the worst way possible; you may feel that it reeks of sexism, racism, classism, and other -isms as yet unknown to social science. Complaining to the author will not do any good, because in the hierarchy of people who have a say in a book’s cover art, the author ranks somewhere just barely above the office cleaning crew and the folks in the mail room. With the rare exception of publishing’s 800-pound gorillas, the author’s traditional role in the selection of cover art is limited to bitching about it afterward.
Problems with the printing and typography of their book. If your copy of the book has Chapter 27 replaced by an equivalent number of pages from Love’s Tacky Splendor, that isn’t the author’s fault. Bad stuff can happen to good books when they go to the printer, and somewhere out there is a printing of Love’s Tacky Splendor that has Chapter 27 replaced by a chunk of impeccably-researched hard science fiction. Those readers — and that author — aren’t going to be pleased about this either.
Problems with the sales and availability of their book. The author’s control of these issues is approximately zero point zilch. Finding out that there are no copies of their book to be found anywhere in the entire state of North Dakota is not going to make them any happier.
In all of these cases, as it happens, the appropriate entity to direct your complaints to is the publisher.
Dr. Doyle's Blog 
LMB must be FUMING about the cover art for Captain Vorpatril’s Alliance. Don’t these so-called artists even READ the book?
On another topic, I personally can’t see that it does much good to complain to an author, period, even about things that ARE under their control. While an informative note saying “Dear Ms Peters, ‘th’ is not a diphthong” may seem like a good idea to YOU, she may have done that on purpose (self-righteous know-it-all unreliable narrator, after all), and has probably gotten 1700 emails about it this week alone!
As far as I know, sometimes the cover artists get a copy of the book to read first, and sometimes they don’t — they get a synopsis or something similar instead.
This probably doesn’t make them happy, either.
One would think that would include physical descriptions of the characters, especially when the author repeats them over and over! But one would, apparently, be wrong.
It is a truth universally acknowledged that sentences that begin with “One would think that…” never end well.
This is relevant to me in that I once complained about the cover art for Kat Richardson’s book “Labyrinth”. My book has a young woman holding a gun, and she has her finger on the trigger. The book was covered on John Scalzi’s “Whatever” blog as a “Big Idea” post. Well, very shortly after I posted my comment, Kat herself replied stating that she, too, wasn’t happy with the lack of trigger discipline. I thought, “Okay, someone who appreciates something as trivial, but important, as trigger discipline. I’ll buy her book.”
And I did.
My stupid complaint wound up getting Kat a sale of the hardcover. Which I understand is better for authors than sales of follow-on paperbacks.
And is the image at the bottom of this web page an audio spectrogram?
And is the image at the bottom of this web page an audio spectrogram?
Truth be told, I don’t even know. I’m using one of WordPress’s free themes-in-a-can, and I picked this one because it was easy on the eyes (my eyes, anyhow) and not so busy it would detract from the entries themselves.
I liked your post and followed your blog just from the headline alone. lol.