I've seen that thing before, did some sock research a few years ago. Don't remember for sure if I've seen any more pictures of men in their socks but the two that come to mind, they were dead when the photo was taken.
One it the alton's in Coffeyville, they look like they are all wearing black dress socks that look like the present issue army wool dress socks.
The other was taken near dodge City in 1874, can't remember the guys name right off hand, but he passed on going down in the Texas Panhandle and stayed around Dodge because he was afraid the Indians would get the hunters down there. So near Dodge he was killed and scalped, although some think it was horse theives making it look like Indians. He had on what look like striped cotton socks borrowed from the Wicked Witch of the East.