This is an area sadly neglected on ALL airlines. It's amazing the amount of rubbish (garbage) that builds up inside the cavities of the sidewalls. As well as the stuff pax throw on the floor, I've seen dust 2" inches thick in one particular part of the cabin(on a relatively new aircraft). Perhaps this is not the fault of airlines, but that of the manufacturer.
Since all airlines are like this, perhaps next time you will choose an airline which doesn't allow smoking (to reduce the chances of a fire).
Rgds.
Q.