Hi
About the wethering of the K's. Even when the K's came out in 45, don't forget that at this time there wheren't any hangars left and the planes had to be hide in forests etc. and covered with whatever was in the forest.
The brutal Winter of 44/45 and the lack of qualitatively good paint, cause of constant bombing of chemical plants, gave them the rest.
I checked a few b/w images of the K's and belive me, they didn't look good at all.
I might be wrong, but on my opinion the weathering is apropriate to the conditions the germans had to keep them in service.
airmess