The lenses for the Flak Jacket also feature a neat Hydrophobic coating, which basically means liquid doesnt stick. Water, and more importantly sweat, just beads up and rolls off. As a guy who sweats a whole lot, I definitely appreciated that.
What bugs me about the hydrophobic coating is that it's not on the inside of the lens. i get more sweat on the inside of my lens than i do anything else on the outside. except for the occasional random flying Sharpie marker.
That stuff might be worth a try, you could make any set of goggles water and mud resistant, but if you have any big name goggles they most likely have some form of water/mud resistant coating. By the way I dont know if any has tried rain off, and is it safe for goggles?
the anti fog later on my lens work fine here in the uk. i am just seeing if there is a better solution then tear offs for mud on goggles. which most of the time isn't big splats of mud, its just the nice shower of muddy water that blocks out your vision.