Welcome to the forums!
From your photos, it appears that the person polishing your coach probably didn't strip the Plasticoat protective coating -- the light gray patches are probably remnants of the Plasticoat. Plasticoat is the proprietary coating that Airstream sprayed on all coaches when yours was new. Typcially the upper panels loose their coating first with much of the coating sticking to surfaces below the beltline. Black streaking is the "tarnish" that the polish is removing and is typically cleaned up with either a chemical or by using a soft terrycloth towel and flour to rub off the "tarnish".
We have one of the pioneering companies so far as Airstream polishing is concerned here in the Midwest. P and S Trailer Service in Helena, Ohio
has been polishing Airstreams for decades, and they can do anything from an "original luster" polish and recoat (new Plasticoat applied) to a mirror-like shine. They polished my 1964
Overlander eight years ago to its original sheen and applied new Plastcoat - - I am still amazed by the quality and durability of their work.