I'm always on the lookout for good business oriented non-fiction. As you might imagine, given my job, I read a lot of "how to sell" and "how to network" and "how to be efficient with your time" kinds of books. (In case you do too, the best book so far is still Harvey Mackay's Swim with the Sharks Without Being Eaten Alive and all of Julie Morgenstern's books)
If you plan to query an agent with a book in this category, you need to mention if you've already had it printed and assigned an ISBN number by xlibris, AuthorHouse, or any of the printing companies in that category.
Why? Because one of the biggest markets for books like this is back of the room sales at the author's speaking engagements. If you've already tapped that market with the book you've had printed earlier, that makes a difference in expected sales.
And if you plan to query about this kind of book, one of the first things I look for is not only platform (ie those speaking engagements) but also your real world experience. That's one reason I listen to Harvey Mackay. He actually worked in a company for many years; he wasn't just a consultant or speaker. This is when you say: "I worked in telecommunications sales for 16 years before becoming a consultant."
There are a lot of people in this world who'll tell you they know a better way to do the job. The ones to whom I listen say "I know cause I worked in that field and this is what I learned."