I decided to replace the liner after getting a hole along a seam in the bottom last year. We repaired it but see evidence of rust on the sides here and there. We left it uncovered over the winter in anticipation of the event and it surprised us that it lost less water than in all the years we covered it! It did get nice and green for spring along with the yard when we typically open to crystal clear when covered.
What surprised me most was the fact that after being drained it is soaking wet under the entire liner. I mean REALLY wet. For years I had a ring of damp dirt around the pool like in the first pic. My neighbor told me that was from condensation. We didn't think we had a leak so took it for normal.
The next image is the spot that really bugged me. When you ran your finger over it it seeped a little. The next pic is what it looks like on the INSIDE of that spot after draining! The liner is different in that spot and I can see a tiny hole. The next pic is what it looks like running the entire side of the liner. I just can't believe this is normal--surely this is a defective wall???
Another thing I did not expect is the bottom of the liner feels thin, hard and brittle while the sides still feel soft and maleable like the day we got it. Has anyone else noticed this with an old liner?
I'm always curious about this stuff, so if this helps anyone, I'm happy.