I think you would be extremely surprised at how clean of an animal that hogs are. I was under the same impression before I began raising them as well. They choose a "special" spot in their pens to be their bathroom, and regularly return to that spot, and use only that spot - never will you ever see them going to the bathroom in their housing or feeding areas. The only odors associated with raising hogs (atleast on smaller scale) is due to mud being prevalent from constant rooting and their high weight concentrations on their hooves creating more mud.