I think this was brought up before, but I do want to gauge other's interest in dynamic weathering anyway. Since we have systems to make trains wet and also snowy (except for GWE stuff. That is snow-phobic) it should be possible to modify existing tech to allow trains to have varying levels of dirt, smoke-stains, rust, shiny-ness, and other weathering. And since GWE has train washes, those could even be used to remove dirt (but not rust, of course), make trains shiny, and wet too (they don't even make trains wet right now.) Anyway, dynamic weathering is a nice way to increase variety in paint jobs without needing to make tons of different textures for clean, dirty, really dirty, etc. and would also be a good way to combat the usual "I think the trains in this pack are too dirty!" "Oh yeah? Well I think they are too clean and shiny!"