I’m 15 minutes into the interview I’m conducting and my job applicant is starting to relax while recounting all the great things he did at his last company. He’s already told me he’s the #4 ranked sales rep for the major mall store he managed, and he obviously feels good about his chances at this interview.

“So,” I said, “When you look at a retail store, ANY retail store, not just yours, what is the #1 thing that will determine whether that store is successful?” I notice sweat starting to bead on his brow.

This question is my favorite in any interview, simply because it helps me understand whether the person has already figured out how to have a successful business. Candidly, the answers would amaze you. “People! The employees are the most important!” said the gentleman I was interviewing. Another interviewee responded with “Having a clean store. The floors need to be cleaned and even the bathrooms.” “Marketing!” stated one woman emphatically. “You have to be able to really tell your story to customers to get them to engage with your brand! (I believe she had just received her degree in marketing).

It’s shocking how many people get it wrong. They look at the external trappings of a store and neglect the fundamental truth of business–which is if you have something people want at a price they’re willing to pay, you will succeed. Product is the secret driver of every business. People, location, brand position, even store layout can help push a successful store to higher levels of profitability and sales, but you MUST HAVE product.

Let me give you an example. It’s well acknowledged that Kmart has gone from being the biggest supermarket chain in the country to a broken system. I have a local Kmart (one of the few left) in my area, and recently I deliberately passed by the new Target and went to Kmart to buy a few items.

The shelves looked like a Florida grocery store hours after the hurricane warning was announced. Of the six or so items on my list, two of them were sold out completely, and the other four I found, but only after some rigorous searching. Was my experience at checkout bad? Absolutely. However, not even the nicest employee or the cleanest store floor could have made up for the fact that I couldn’t find what I needed, and my time is too valuable to try again.

In any business, whether it’s a retail store, a service company, a restaurant or a resale franchise, your product will make the difference between failure and success. Have the right product. Price it right. Make sure it’s fresh. Mark it down when it doesn’t sell. And constantly evaluate it. It’s amazing how everything in business comes right down to that.