Aressera said:
Here is a real picture of water to illustrate the correct behavior.

Yes, I've spent a fair amount of time studying why we see the stretched specular reflections on a sunset over water and I understand the reasons why it happens.  I just hadn't considered that the microfacet calcs …

The theoretical parts of this article require some knowledge of optics and electromagnetism, however the conclusion and final result (a practical implementation of single-layer thin film interference in the context of a BRDF) do not. You may therefore wish to skip the theoretical sections.