Here is a couple of basic ways I like to uncover DEMAND.

Hello Mr. Grocery store manager. I come into your store every week and I got to thinking. "What products do you find that you can't keep enough on your selves that your customers keep inquiring about?"

Hello Mr. Hardware store manager. I come into your store often and I got to wondering, "What products sell better? And how often are you running out of them?"

When they tell me I then ask, "How do these companies get their products onto your selves? I mean, who would they contact about bringing a product to your business to sell on your selves?"

Once I've uncovered DEMAND and distribution data, I would then move on to the next competitor and ask them the same thing. Once I get a general consensus of what grocery stores or hardware stores sell the most of, then I know what product to look for.

Grant it, it's basic geographic leg work, but the data I bring away from meeting these people will keep me focused on their DEMAND and not my LOVE of a product.