Recently some thing odd is happening in my save. Some of my NPCs are naked. I first noticed in Valfar, he was wearing underwear with the bear helmet on, I solved it using it own clothes based dialogue. Then I noticed in Vilja, it happens sometimes, when crouching for example, since I use CBBE it is not a bad sight at all , but it is kind immersion breaker.

The last mods I installed, not sure when this bug started, are:

Wet and Cold
Unofficial patches Skyrim 1.2.7
Unoffical Dawnguard (latest)
Become a bard (it updated yesterday)

Maybe it is related to one of them?