The natural metal A-12 trainer on display outside the Los Angeles museum shows what a weathered A-12 looks like- not rusty. As Stephan says- we won't see "rust" on the titanium skin.

I have seen her up close, and she looks weathered.
A-12's first flew in natural metal and a touch of black on the (hotter) leading edges, nose, tails etc. Finally they went to all black, and all the operational versions that flew in the later 1960's were all black, and went into storage that way. It seems that only this sole A-12 and the M-21 drone launcher (preserved at Seattle) remained in the two tone natural metal.
Note this photo at Palmdale of the A-12's in storage. You can just see one two tone aircraft near the top. Also note the red/pinkish panels showing up on a few of them. My guess these pinkish sections are unpainted special fiberglass used on the chines and some leading edges. The A-12 and SR-71 designs included leading and trailing edges made of high-temperature fiberglass-asbestos laminates. Note we are seeing some red peeking through on both the titatium and figerglass areas of the picture on the A-12 at Huntsville. I conclude primer.
So we have some red showing through the A-12 at Huntsville. My guess is we are seeing reddish primer as the black paint has faded.
I offer this thread title could be "A-12 rattybird..."
