Sometimes you can’t tell if your book is bad or great. A lot of times you’ve fallen too far down into the rabbit hole to climb back out and look down it again. You’ll spend hours working on your book without knowing if it’s any good.
Sure, you can spot an off-sounding sentence, identify all the way up to a chapter that needs to be deleted, but you don’t know if the book’s any good. You don’t know if you executed the plot right, or if you wrote justice to your idea. Hey, you may not even know if the idea’s any good to begin with. Again, sometimes you can’t tell if your book’s bad or great.
This happens to almost all writers – it is not uncommon, and there are things you can do to fix it. My advice? Beta-readers. Make a list of trusted people to have read your book, and ask them for their most honest feedback. Ask your readers the end-all question: should I scrap, or should I keep, this book?
However, I wouldn’t throw away a book I’ve spent painstaking hours on unless the great, whole, vast majority of people say the book is a lost cause. Even then, remember it is your decision as to your book’s finality – you know it better than anyone.
Also, know not to “put all your eggs in one basket.” Just because you see one of your beta-readers as really qualified and smart, doesn’t mean you should disregard everyone else’s advice or take all of their feedback without thought. Even though that person may be smart and amazing, remember that they are just one person out of many, many types of readers.
Here’s where writers get stuck: they don’t want to show people their work. But if you’re planning to publish, one way or another, people are gonna see your work. You don’t want a potential agent to be the first person, outside of yourself, to read your manuscript. And if you’re self publishing, you don’t want the masses to see it before some outside opinion, either. If you’re writing simply for yourself and never plan to publish, that’s fine, it doesn’t matter. But in my opinion, a book is not “done” and ready for publication until you let people review it and give feedback.