Well, I now have some cargo/fatigue type pants of silicone treated fabric, and it's pretty amazing how stain resistant it is. My knees ground into some mud and it dusted away completely a few hours later. It's water resistant, not waterproof, but it's as breatheable as regular fabric. It'll be interesting to see how durable it is.
Of course, I'd like to see it on regular baggy fatigues. The ones I have are not as loose as I'd like them- given that my legs are pretty thick compared with my waist...