Every business has an idea of who its customer is. The bookkeeper serves restaurants. The photographer shoots weddings. The web designer works with local retailers. That picture shapes the website, the pricing, the marketing and the way the owner describes the business at parties. When sales start to slow, most owners try harder to reach that same customer.

But look closely at almost any small business’s client list and you’ll find a few who don’t fit. The bookkeeper has two clients who are dentists. The wedding photographer keeps getting hired for corporate headshots. The web designer has a handful of therapists who found her by word of mouth. These customers are easy to treat as exceptions, nice extra income that has nothing to do with the real business. Sometimes they’re the most important clue the business has.

The stories that show up on Turnaround Thursday tend to share this pattern. The founders didn’t invent a new market from nothing. They noticed someone was already buying for a reason they hadn’t planned for, and they followed it. You can run the same search on your own business in an afternoon.

Start by pulling your customer list from the last year or two and marking anyone who doesn’t match your intended customer. Different industry, different size, different reason for buying. Then look at those names as a group. Are they paying more? Easier to work with? Coming back more often? Did they find you without any marketing at all? Any of those is a sign of demand you didn’t create, which is the most valuable kind.

Then ask them. A short note works:

You’re a bit different from most of the people I work with, and I’m curious. What made you choose me, and what problem were you trying to solve at the time?

The answers are often surprising. The dentists picked the bookkeeper because she understood a billing issue their old accountant didn’t. The corporate clients liked the photographer’s relaxed, unposed style, which is rare in headshots. Answers like that describe a need you’re already filling, for a group you’ve never marketed to. If there are more people like them, you may have found the next version of your business.

This doesn’t mean dropping your current customers overnight. It means testing. Write one page of your website for the unexpected group, mention it to a few people who could refer more of them, and see whether they respond. If they do, you’ve learned something your original plan never could have told you.