How to validate product-market fit using paid ads without burning cash

Paid ads seem like a tempting shortcut for validating product-market fit because you can put an offer in front of real people fast and see what happens. But that also makes it easy to confuse ad performance with actual market fit. A clever angle, a cheap click, or a decent landing page can make something look promising even if the product itself is still shaky. On the other side, weak creative can make a good product look dead before it gets a fair shot.

So I am curious how people use paid ads for validation without turning it into an expensive guessing game. What do you test first? Messaging, audience, offer, conversion event, pricing? And what signals do you actually trust at an early stage? I like the idea of using ads as a way to learn quickly, but only if the spend is teaching something real. How do you validate product-market fit with paid ads without lighting money on fire in the process?