Yes, asking customers what they want isn't usually that helpful. However, listening to customers is very helpful. It's not easy, but by listening to customers

Yes, asking customers what they want isn't usually that helpful. However, listening to customers is very helpful. It's not easy, but by listening to customers we can identify trends that help us answer: "What should I build?". Then, instead of building the whole tractor (or rocket ship) we can show them a model (or prototype) and gauge their reaction. In my case, with the sneakers, I could have purchased my own pair online ($90), and shown customers and friends to see if there was any local demand. That would have saved me a lot of money! (I ended up having to sell most of the shoes at a loss)