I have had blood, mud, general camp crud, on my BP cheapo breathables.In the past usually once it all gets built up enough that I start to notice it all. I break out a clean sponge with a little dish soap and wipe em down then take the hose to them.
There is how ever washing machine instructions on the inside of them. Im just not willing to let my machine put my waders where ever those lost socks get to.