[Daktest]

If it's a small enough company, I would definitely suggest interviewing the founders from the perspective of an investor. Your line of questioning should be focused on asking them/yourself, "why should I invest my time in your company?"

This should raise all sorts of questions like, what's the value-prop of your product/service, what's your go-to-market plan, what is your experience building and scaling companies, etc.

If you can't personally be interested in the company after speaking to the founders - I think it's likely that it won't be of much interest to you.