Where I come from, dirty, illegible, damaged landing gear pin streamers are replaced. Spares are always kept by or available to line maintenance crews.
You know why they are there so it's simple...missing or damaged streamers need to be replaced. Even the holding rings that attach the streamers to the pins need to be checked.
The downside is that to carry out any maintenance, you need a I.A.W procedure. I'm not aware of a direct AMM reference.
The Standard Practices Manual barely covers it.
What do others think?