Sounded like a great quick trip. Mule Ears (obviously

is one of my favorite places) is a great place to use as a base camp. While I have criss-crossed the Smoky Creek flood plain several different ways and directions I have never been farther south than the southern end of the Mule Ears peaks. I now will have to go on south and find that spring where the braided drainages all come back together. Makes sense there would be a spring there.
For future reference, you can easily hike cross county to Smokey Spring. The worse part is cutting across the braided washes of the creek once you split off of the trail. After that, the vegetation isn't quite as dense. Head toward the left of the "sphinx" looking rock and keep bearing left.
Robert is dead on, if you stay more north and to the left of the "sphinx" rock you quickly get across the lechiquilla choked flats above the washes and hit a more bad land type area with much less vegetation then it is an easy stroll up to Smoky spring.