I recently watched Salo for the first time and I must say I fell in love with the look of the interiors.
I know Pasolini used Arri, and maybe a mitchell cameras, and the only shot of the ceiling that I have seen looked like he used several giant chimeras - long cylindrical shaped suspended.
It was circa 1975. But I would be interested in discussing how to achieve the same style of lighting. I have judiciously included some screenshots, that would be suitable given the nature of the film.
And that's about all I can share as far as screenshots are concerned. It has a quiet, subdued look. Muted color palette. I wonder if there were other film stocks available in Italy that are no longer that might add to the specific color look. I am awating my Blue-ray version so that I can watch the 176min documentary footage which will hopefully shed some light on this... light. HA!