Are you referring to at the end of a product demo "what do you think, would you buy it" type situation?

If you're talking about market research type of interviews: I don't ask this anymore because it puts people in a weird spot and they never want to say no to you. Plus, in general, you get way fewer insights from people when asking yes/no questions. But I do ask closely related questions. For example, I describe key features and for each one, I ask "What's your reaction? What would be the impact on your day to day if you could have that? How much would you pay for that". And you pretty much get your answer, with more insights on why they would buy it or not.

There's this mentor called Dan Lok, I don't know if you've heard of him. He's mostly into high ticket sales so he knows how to deal with clients well. He once said in a video that even if you ask someone "would you buy this?" it's useless. Someone who's truly excited and would want to buy your product wouldn't just say yes, they should get so excited that they should just "shove money to you" and want to buy. So according to his approach, if you present your idea to somebody, it may be better to ask for just a general opinion on the product (no "would you buy") but make sure you push their pain points and market it right, and then check their reaction. It's all about reactions. If you want to learn something about anyone, never listen to what they say but watch how they act. Sometimes it's not synced.