Just made a discovery the other day and I figured i'd share it with the community here in case anyone is in a similar situation. So if you have a carpet like this one (i bought this used from Ebay):
(this shot is after cleaning and power-washing)

So after a deep cleaning, there's still quite a bit of discoloration and fading here and there, and stains that didn't wash out. So after restoring my trunk carpet,
I've determined that THIS is the best and most forgiving spray paint to restore and touch up this particular color carpet.


I forgot to take decent after shots after taking the carpet inside to avoid the rain, but i wanted to get this post up before i forget. So new pics will be on the way and i can show you how well it works to blend out all kinds of discoloration from whatever you couldn't remove with chemicals or water/soap. One other detail i noticed is wherever i sprayed doesn't seem to feel any different than unsprayed areas. So that was a cool unexpected result.

 

I power washed mine also because it had mold on it from the roof drains, draining water inside the car.. Gotta love Nissan designs..
I also had few spots that were brighter and some darker but then again, it's not a Bentley so as long as it don't smell like dead fish, i'm good with it..