Upload & Sell: Off
Well, I got a second copy of the Sigma 35mm f/1.4 lens.
The first copy I had showed massive focus accuracy problems on the side AF points, progressively worse as you moved away from the center with the center column being perfect.
I had tested my D800 for left AF point focus problems with a Tokina 16-28mm f/2.8 lens. It appeared that I did not have the left AF problem. I would've been surprised as I had the problem with my first D800 last Summer and figured it surely was resolved in all new bodies by February when I bought my second D800 body.
Today I learned that I was wrong. This body DOES have the left AF focus problem. The Tokina 16-28 was just so bad on the sides that it was indiscernible even in careful test shots. By contrast, it was easy to detect the problem with a 14-24mm f/2.8 lens last year. However, becoming aware of the problem with the new copy of the Sigma led me to try my Nikkor 16-35mm f/4. Even though it's at f/4, the focus accuracy is consistently off, it's just not as damning at f/4.
Last Summer when I found the problem on my first D800 body, I did so with the Nikkor 28mm f/1.8 lens. You really need a wide and fast lens to clearly see this problem.
All that said, the new copy of the Sigma lens is definitely better. The previous copy was so ridiculously far out of focus it couldn't be corrected with AF fine tune. This lens can be, though it won't as that would cause problems with other AF points. It just means I'll be sending my D800 in for repairs, just like the last one.
So the lesson today is this: don't count on shitty Tokina lenses for testing AF performance and it's possible that BOTH the body and the lens are working incorrectly.