It isn’t. I touched on this a bit before, but I want to go into it a little deeper because all too often I’ve seen authors try to convince publishers and agents in their proposal that their book is targeted to the broadest possible audience. I understand the thought behind this, but ultimately you are doing yourself (and your book) more harm than good.
Publishers want to see that your book is focused. In trying to make it all things to all readers, authors tend to lose sight of the fact that there is a specific audience to whom they should write. For example, if your book is about beekeeping, in your proposal you should say that your target audience is apiary enthusiasts. These are the people who are most likely going to be actively looking for a book on how to set up a beehive. Once you’ve targeted this set of the population, make sure you get to know the market. Publishers (and agents, for that matter) love statistics. They want to see, in numeric terms, the size of this particular demographic in addition to its book-buying and general spending habits. This information helps publishers determine how they’re going to market/promote your book, the amount of dollars they should budget on behalf of this, and –quite frankly—whether the target market can support another book on this topic.
Also, you have to think about where your book is going to be shelved in a bookstore. Booksellers rely on the information a publisher provides them about a book’s target audience. It informs the bookseller where to shelve the book. If, on the back cover, they see more than one category listing, chances are your book won’t be shelved where—in this case—apiarists are most likely to look for a book on the subject. Therefore, because you weren’t specific enough in your initial audience breakdown, your book may become difficult to find which serves no one’s benefit, least of all your own.
When working with authors on their proposals, I always insist they list the Primary Audience first, followed by a Secondary and sometimes Tertiary audience. It’s good to demonstrate that your book has the potential for mass appeal; however, typically the focus should be on that first category of readers. By doing so, you are showing that you know your potential audience, that you’ve done your research, and that you have a realistic perspective.