White Patchiness on Plaster over Rock Lathe Rolls

Question

I have a 1950s build house with plaster walls installed over rock lathe (vs. wood lathe). In one room, the walls are showing white patchiness throughout. They feel clammy and have no "slip" to them. In the rest of the house, I can glide my hands across the walls. In this room, there is friction. The problem is happening on both interior and exterior walls. The ceiling does not leak. The crawl space is very large, with a vapor barrier in place, and the area under the room is dry. The heat source for this room is cast-iron baseboard radiators. During the winter, this room is kept about 60-65 degrees.