I was with my wife and kids in our Jeep on the Hell's Backbone road down near Boulder, UT. It's a good dirt road, but it has some really freaky dropoffs, and great scenery. And it was just us out there--we hadn't seen another vehicle for miles and miles.
However, it's a really long road, and nature happened to catch up with me, to the point where I needed to do a number 2. I hiked up the hill opposite the cliff side, found a level spot near a tree, and proceeded to do as the bear does when in the woods.
As I was in that vulnerable mid-squat position, I glanced behind me and noticed that the road must have curved back up around my hill. I say "must have" because I didn't see the actual road, but instead I saw the first few vehicles of an approaching Jeep safari, with about 8 vehicles.
There I was, outlined against the sun on the top of a hill, in plain view. I finished my business as quickly as I could, gave it a very perfunctory burial--I wasn't as ecologically responsible as I would normally be--and ran down the hill to our vehicle. I did NOT want to be seen coming down the hill when they came around the bend so I could at least pretend that must have been some other schmuck up there baring it all for the Jeep safari. To be safe, though, I hid behind the lowered sun visor as we made our way past.
In summary, I highly recommend the Hell's Backbone road. But be sure to take some TP, and be extra careful which direction you point your posterior.