Last year I was given a partially used bottle of Rodinal; came in a glass bottle with a rubber cork. I have no idea how old it was, probably decades old. It was almost black in color, but worked just fine.
I've got a two year old bottle that is getting quite dark red, but still produces results consistent with those from years ago. I have some bottles that have been unopened for at least one year, perhaps two, that have very little color at all from what I can see through the bottles.
As we have seen, the color of Rodinal is no guide as to its quality. The lack of color of XTOL is no guide to its quality.
Dilute a small amount of Rodinal 50:1 with water and aerate it thoroughly. See how dark that small amount of oxidized Rodinal can make the solution.
The test of Rodinal is in the use. When you get worried, do a snip test. In fact, you should do one with a new bottle just for the record. Keep the result for comparison with later tests.