A friend of mine from when I was growing up is a true blue professional hacker for the US military. He gets paid to hack security software. Specifically, he writes software which figures out how other security software works. He figures out what the requirements are.
He prods the software, notes down its behaviors, and then uses that feedback to construct more ideas for tests. Based on the requirements he gleans, his team can build exactly the same thing from scratch, if they decide that’s what they want to. Geeks call this technique reverse engineering.
You can take the same approach when trying to sell a new product. While it might not always feel pleasant, the market tells you what it thinks by giving you feedback. (No feedback is feedback too.) I’ve put up offers which seemed like they’d be interesting for my target audience, but they didn’t sell.