I have noticed that in city lights reflected on the water are very often smeared more in the vertical direction (relative to the reflecting plane I presume), than in the horizontal direction. See, for example, pictures here.
I can't figure out why. I think it would make sense if the waves happened to have their wavefronts perpendicular to the line of sight, but I think this is unlikely, as it appears you can see it from many angles.
Thinking about it, maybe what selects the special direction is that the creases in the water that have wavefronts perpendicular to the line of sight cover each other up while the ones with wavefronts parallel to the line of sight don't.
This may mean that as diffraction off small features causes the large features in the angle distribution (as it's a Fourier transform), maybe this causes the preferential spread. Also it would explain why I don't remember having seen this effect unless I am looking to the water at a pretty slanted angle (large angle between line of sight and perpendicular to the surface)