Dave Frary covered layout cleaning in his book on model railroad scenery. Basically, you vacuum as much as you can, using those small attachments made for cleaning electronics where necessary. You scrub down hard surfaces like roads, water ways and structures with soapy water and soft brushes. You spray large areas of foliage with diluted green washes, repaint and add new flocking and ground cover where needed.
There’s a section on preparing the layout room to mitigate some of the dust problems, like sealing bare concrete and installing walls and ceilings in basements, air filtration and so on.
You’ve got to imagine that cleaning and maintenance is a full time job on those big public layouts. Imagine having to clean Miniature Wonderland in Germany!
