Trust me, I know how to wash cars. I've been detailing cars since I was a young teen (that'd be 40 years now).
You are correct on the Pagoda garage. Dust occurs, but not to the degree of the daily. We do get our share of pollen, cottonwood, dandelions, leaves and debris.
You are right, an epoxy coating on the floor is the way to go, the paints just won't last...I went through three iterations of that in the daily garage before spilling for the epoxy (slurry, not paint).
I don't know how much I'm in the minority in avoiding water and certainly commercial car washes on my classics. For heavier issues, such as a good bugging like on my 200 mile drive to Chicago and back, I'll use a damp rag shortly after returning to loosen and remove the bugs. For a rain spray, same trip to chi town, a damp rag will remove any light dirt. Then onto the detailer and microfibre. Heavy dirt, heavy dust, heavy pollen, mud, tar, road paint, caked on old bugs, dried up gas spills, etc., yes, water and a soft, soapy mitt are the way to go, even clay if need be. And at that, I might only do the affected section like the wheels, grille and rockers. I haven't had to deal with that situation on the classics.
Bottom line...everyone has their preference. As long as the cars are kept cosmetically presentable and mechanically sound, all is well.
P.S. the 600 miles I've put on the car have essentially been since May. The car is driven at least twice a week.
