Mods do one of two things with snow: They will change the snow textures placed on rocks and stonework, or they will mess with the snow textures on the landscape.

I've never had a problem with the snow covering the natural landscape; I find it convincing enough to enjoy. But the snow on rocks and stone is so bad that it pulls me right out of the game; I often have to stare at it and qonder why it has to be so lousy.

http://elderscrolls.wikia.com/wiki/Bleak_Falls_Barrow_%28Location%29 is a great place to measure the quality of these particular textures. Without modification, the snow textures applied to man-made objects comes direct from the 1990's. Snow looks like flat, featureless house paint in the vanilla game, high-resolution textures or not. The popular http://www.nexusmods.com/skyrim/mods/10383/? mod makes that flat white paint look like slightly textured white paint, and I suspect that the screen shots advertising the mod were only possible thanks to additional ENB modding. In game, the Better Dynamic Snow does not have the sparkle of genuine snow—it certainly doesn't look like the screen shots.

I have to ask you guys if anyone has managed to mod the snow textures on rocks and stone well enough to convince the sighted. You can't ask these kinds of questions over at the Nexus Forums and get a straight answer, for obvious reasons.

I think these rocks with snow are nifs, they are not rocks on which you put a layer of snow. It would take a lot of people and time to redo all of them.