Book publishing, like with any other creative product, is primarily about business, not art. Most normal publishers only want to publish books they think will sell, and will publish manuscripts that have possibilities of reaping good sales. Sensible publishers will try to publish good manuscripts under the logic that quality is appreciated. Vanity publishers really don't care either way and will publish anything, as they make their money off the authors rather than the audience. Some publishers go a step further. They churn out books as if they were a machine, and authors were merely cogs.