I have read a lot of eBooks since I was given my first kindle four years ago. I would have to say three quarters of the eBooks I have read in the past four years were either poorly edited or not edited at all. Many never went through a beta reader or a proofreader and it shows in the writing. It sticks out like a penguin in the middle of the dinner table! No matter how great your book cover is, or how great the blurb of your book or that you hired someone to promote your work, or paid to have it reviewed. Bad writing is bad writing. All the fancy trappings are like dressing up a rotting body. It stinks. Word of mouth is one way your book gets promoted by readers. Do you want them to go around and say, “Don’t bother buying this book; my four year old writes clearer sentences.’
Sure, a writer will say they had people read their work before publishing and they said it was fine. Who were they? Friends, family members? Your spouse or significant other? They tend to tell you what you want to hear, that your book is great, go ahead and publish it. They do you no favors and you learn nothing about what is wrong with your story.