Borderline poverty vs borderline pass

Hi

As I understand this

Borderline poverty - almost poverty but not quite
Borderline diabetic - nearly diabetic but not quite

However,
A borderline pass - almost a failure but still a pass
A borderline failure - almost a pass but still a failure

Do I understand this correctly? If so, why is the logic is reversed? How do I know which is meant if a person uses a different example?

Thanks