I am not sure how the manly smell of horse manure has been elevated to some iconic status redolent of a "real America." It's brilliant PR.
As I stated in another thread "a sorely missed component to these back country discussions".
I once attempted an ill-timed hike on the Bright Angel Trail (in Grand Canyon) It was my bad fortune that I chose to mosey down the trail right after a re-supply train heading for Phantom Ranch(?) had just been through. After a couple of miles of gagging over the urine smell/droppings on the trail, I bagged the hike and got some <fresh> air.
Not sure if mules smell different than horses, but I was definitely not having a nostalgic moment.
there's still major can dumps hidden around the older and less visited packer camps
This reminds me of a term that I heard used for such trash heaps: "artifacts". Yeah, right, as I said: trash heap! I have a bad attitude about "artifacts" because I once took a 15 mile round trip dayhike to a "pristine" (see where I am going by the quotes) lake that was a 1,000ft descent that one would have to lumber out of in order to reach the final destination. After hours of blister filled misery, I reached said 'pristine lake' and was greated by a 6' artifact-cum-trash-heap that had probably been growing for 100 years (polite folk that they were for keeping the crap all contained through the ages) Ten minutes later, I was cussing my way back out of that 1,000ft pit cum lake (called Lake Warren; located in the Tahoe Nat'l Forrest -- a brutal day hike)
