I have some ACU camo nylon pouches, and I think it works great on the eastern Sierra Nevada Mountains where there is lots of grey granite rock and light dirt. Although, I am currently no where near those mountains, and ACU does not blend in well in the Redwood Forest. So, I have purchased some Dharma Acid Dyes (for use on wool, silk, protein fibers, and nylon). It was easy to use: just mix some dye with water, add fabric, heat to just before boiling, add some vinegar, and stir occasionally. The directions say to let the fabric soak for about 30 minutes. I kept the fabric in the solution for about 15 minutes, so my results might have been darker.
I tried three colors, from left to right: soft tan, pistachio, and olive-brown.

I think I will mix the soft tan and pistachio and see what I get, and also both separately again but immersed for the stated 30 minutes to try for darker results. I like the both of them more than the olive-brown, which would have been great for my suburbia night missions (reminiscing on teen years) years ago.
I know many of you cringe at the mention of ACU, so I just thought I'd share.