The rod is not shiny at all.
It constantly moves, so it can't accumulate much of rust, but a sane inner rod will look like a high-quality mirror even after running around the equator 2 or 3 times.
Its main failure mode looks like this:
- The rubber parts age and at some point tear.
- Dust and sand adhere to the rod.
- When the rod moves, the accumulated sand and dust grind the rod and the o-ring that keeps oil from leaking.
- Oil starts leaking, attracting more sand and dust and accelerating the degradation of the other rubber parts.
- After losing enough oil, damping function is gradually lost.
It is possible that it still retains some damping action, but at this point the degradation is self-accelerating.
Of course, depending on your tolerance to increased vibration, poor braking, poor curve handling, poor pothole handling, increased wear of the tires, bearings and the other suspension parts, your ability to drive safely a broken car, the available funds, your jurisdiction's tolerance to broken cars, etc... you may leave it as is, e.g. for an year or so.
But you probably shouldn't.