Under other circumstances I would agree with this sentiment, but in this case there was not a real 'solution' to a real 'problem' - and so I'm not sure there is much for anyone else to learn from my mistake. I encountered difficulty simply because I was adding textures to the wrong model (I save my work in Blender often and have many iterations of the same model - some of which resemble one another very closely upon superficial inspection). I do have what I believe are pretty good naming conventions and so normally things don't get mixed up. In this instance I simply opened the wrong file.
If there is a lesson to be had from this, it might be: Make sure you're working on the right thing. Or, make sure you're working on what you think you're working on. Or something.
Peace,
cs
