I see your point. But you are simply solving IRR using a stream of cash flows. Based on your formula,
C0 + C1/(1+r) + C2/(1+r)^2 + Cn/(1+r)^n
As long as you can sell your property at a price(Cn) higher than C0, the above formula will always be positive if r is equal to 0. It's contrary to what you are trying to say.
It's correct to say that the higher the IRR the better an investment. But it really doesn't have anything to do with positive cash flows.