This Gold that you want to clean from smoke buildup....is it goldleaf or some other glazed metal leaf, or is it just paint?
My suggestion which comes from several expert theatre restoration professionals is to use bread. Yes BREAD. White bread. The solf packaged presliced type. Like Wonder Bread. No Italian or French please! Remove the crust and ball up the remainder into a nice ball and use like an eraser. It should pick up the dirt without harming the surface beneath. It will take quite a lot as it will fall apart quickly....but, hey...bread is cheap! Give it a try on a small area and see what happens...and let us know.
I have done this and it worked nicely. I have done it on painted plaster decorations over 65 years old, and it brought back the original colors very well.