What makes you take an independent film project seriously?

For writers, directors and producers working on independent films:

When you come across a project that you're genuinely interested in, what makes you think: "This could actually become a film"?

Is it:

• The screenplay itself?
• A strong director?
• Attached talent?
• A realistic budget?
• A clear financing strategy?
• A production company already involved?
• A strong pitch/deck?
• The marketability of the concept?
• Something else entirely?

And on the other side:

What are the biggest red flags that make you lose interest in a project?

I'm especially interested in hearing from people who have actually developed, produced, financed or packaged independent films.

There is so much advice online about "writing a great script", but much less discussion about what makes a project production-ready.

What have you learned from experience?