I just got done cleaning the underside of my RV hood. It was dirty and I didnt like the way it looked so I washed it and waxed it... Cleaned everything else under there too..
I spent $130,000 for a MH. Keeping the engine bay clean is something I want to do. I autocross a Miata and do the same to the engine compartment. At every event there will always be someone that compliments me on how clean a 25 year old car is.
Both the Miata and MH are hobbies, I will take the extra time to keep them clean.