I am finishing up a gun right now that got bluish grey spots every where a drop of sweat landed on it. Not the normal dirty looking spots, but deep colored blotches.
The stock had real nice figure but didn't "pop" at all from the aqua fortis. I had experimented on a scrap from the blank and was worried that this might happen from what I saw on the scrap. I tried the aqua on a scrap from another blank and it "popped" just fine, so I know it isn't my aqua fortis. I ended up doing some staining on it to try to show the figure, but it is a pretty "dead" piece of wood as far as that goes. Nice hard piece with good figure in the raw, but it just wouldn't show much figure. I figure it must have some sort of minerals in it that reacted with my sweat.
So, I hope your piece will finish up nicely, but mine sure didn't!