Can't Keep It Looking Good

frequent washing helps
my 2002 komfort with painted corrugated aluminum siding looks new.
i wash it after every use , without exception.
i use one of those 9 inch wide X 3 inch deep soft bristle truck brushes mounted onto a 6 foot handle.
i pour a 5 gallon pail of hot water.
spray a section of trailer .
rinse the brush out in Hot water
lay down a stripe of palmolive on the truck brush
wash my reasonable size section
rinse it off with the garden hose
and repeat.
i use a couple of different wash mitts to get the intricate spots.
I detail my fancy german cars
i use a clay bar to get them nice
i polish my cars very frequently
they are very shiny
my TT sits 90 % of the time under a 3 sided shed
it always looks good .
it is shiny enough just by washing it very frequently .
i have no black streaks

I've found that most stains are easily removed if you get to them before they are baked in. My guess as to the biggest difference is the number of times you wash the car/truck compared to the trailer.

Same with my front end. Black with bugs last year after the Love Bug invasion and stink bugs mixed with mosquitoes and black flies. Took it to Camping World and let them was polish and wax it for 260. The guy earned his keep.

Try Blue Coral Wash and Wax, as it has Bees wax that builds evey time you use it. That fills the voids and keeps dirt from surfaces. If you need to remove any mold add Clorox to it which cleans even awnings as it then waterproofs the material. Usualy two to three cups of each then fill wash bucket 3/4 way with water. A long handled brisle brush does the scrubbing best.

imho, Zep looks really good on mine

No Issues with my sides/back. Wash with RV Glo and wipe down with Mothers detailer. Now the front cap is a whole nother story. Can't get that sucker to shine for nothing.

i use greased lightning, that stuff will clean off streaks very easy