Some years ago I took a tour of the Old Fitzgeral distillery outside of Louisville, Ky. They had these big low circular vats of corn mash fermenting and they told us that that it "smelled really good," but that we all needed to bend down near the vat and take a real good whiff of it to really appreciate it. What a dirty trick. I bent down, took a deep breath and someone backhanded me across the side of my head so hard it knocked the stink out of me. I was so mad! Then I looked up and saw that the same thing had happened to everyone else. The tour guide was just loving it. Apparently about a foot or so of co2 was pooled over the mash and breathing that stuff in is certainly not a recommended thing!