There are a multitude of articles bemoaning the lack of editing that goes into independently published books. (In fact, I wrote one myself.) However, I think the point that is missed in these articles is to identify the types of editing that are needed.
Book editing requires more than just having someone go through and check for spelling, grammar, and punctuation. To ensure that your book is truly the best it can be, you should also have structural, developmental, and content edits done. These types of edits ensure that your book and your story have a smooth flow, good pacing, no plot breaks or inconsistencies, consistent POV (point of view) or recognizable POV breaks, clarity, believability, and above all, readability.
That’s a lot to ask of one person, which is why you usually need several editors to go through your manuscript. Structural editing for fiction and non-fiction is a talent and a skill, honed by years of practice and a lot of knowledge about what makes a good story and a great book. These types of editors can identify where the plot drags or goes off course, explain why, and then give you suggestions as to how to fix it. It might be that you introduced a character that is flat or you took your story on a side-trip that was completely unnecessary. But unless someone points this out to you, you may never see it; because this is your ‘baby.’
Most authors fail to see the need for trimming storylines, eliminating characters, or swapping out chapters, and that’s why structural editors are so necessary and so helpful. Authors, like most artists, tend to be very protective of their creations, and the last thing we want to hear is that we need to “fix” it or change it. To us, our creations are perfect, and having someone point out the flaws in our creations hurts.
As an author of both fiction and non-fiction, I have to admit that I’ve seen my share of red and blue pencil marks on my manuscripts, and while it hurts, it hurts a lot less than having a reader tell me that they didn’t like my book, or that they liked it until page 110, where it rambled and the story got lost. I would definitely rather have an editor help me fix my manuscript than lose a reader because I didn’t want to change my perfect creation.
Once you have the structure and content set, then you need to bring someone in to check the spelling, grammar, and punctuation. And don’t think that running your system spell- and grammar-checker are enough to get you through. I can’t tell you how many times the spell- and grammar-checker has told me my manuscript was perfect, when, in fact, it had numerous egregious errors (such as homonyms or homophones that would, and should, be caught via context and content). Spell- and grammar-checkers are notoriously unreliable. While they might catch the double “the” that you accidently typed, they rarely seem to be able to use the content to determine correct word or punctuation choices.
So, if you want to ensure that your readers have an enjoyable time, you need to give them the best product you can. For most of us, that includes trading or paying for the services of a book editor who can help us perfect our creations.