what’s something that could instantly make you say ‘this is a bad idea'?

hey ph crew 🙌🏻 I’m working on an idea that I think solves a specific pain point. → what’s one early red flag that told you your idea wasn’t solving the problem you thought it would? → any quick tests or methods you’ve used to validate a hypothesis before going all in? appreciate any experiences or cautionary tales here. would love to avoid building something that only i want!