The models are a compromise to use all sorts of material on the same mesh. The idea is getting away with 1 material using 1 texture for base colors, 1 for blood and 1 for dirt using masks because the are very small for the all models.
If needet just switch between all textures and use every texture you want.
Was thinking about sometihing similar on how to use it. But as you move to fast with a rail shooter i guess i will need to do this a little different. Like starting and see all this filled bags and covered bodys. A little later you see empty bags like in this picture. I think if somebody see this he knows there is something around there.
Was trying if i can get away using the same material and it kinda works. I noticed something strange while trying, seems like i did something wrong within the layered material so the colors somehow depend on the angel on the light and/or rotation of the mesh 
