Depends on the product. (E.g., funeral service?)

Well...let's agree to disagree because I say the hallmark is whether the business model is sustainable, which I'm not sure your heuristic completely fields. Deal? To be fair, it did look like the business model had legs here for a while.

Nor really, most products aren't designed for consumer use. If a company makes nuclear weapons, I hope the board members are not using them. Board members may not have a use for straight jackets, body armor, cash registers, oil rigs, industrial equipment, commercial fishing vessels, you get the point.

Even if the product is great, the business model could suck and the company will fail.

That's useful if they're not all cranks trying to sell perpetual motion, organic food, or placebos.