Who indeed cleans their layout? For some reason it would appear that Americans judging by the number of times the question is raised, are! In my current tinplate life, I never bother; after all has anyone ever seen a clean railway? It was a little different in my OO days as dirt makes a difference if only on track head. In those days, I did try loose ballast only to see it spread mainly due to vibration.
Nowadays, the layout is covered with excess foliage material off bushes and trees, dust, dirt and the remains of a few spiders which may offend some but with a tinplate layout, no one notices or cares.
Brian.