Oh the bugs it dirt can get out alright! Painted sealed wood too!(I killed three tree beetles not really native to Michigan under, and around my new layout)
Coffee dried, and sealed in a can, won't grow mold.
Ground up and wet, it is ideal for mold growth.
I'm sure other areas climates, even some in Michigan, would have no issues.
I've seen moist southern climates where Id expect it to be worse, but I don't really know about that.
