So I just got my packages delivered from Beach Camera. It seems reasonably well focused to me, although I'm not expert. I've seen at least 2 different focusing test used in this thread, as well as miscellaneous shots of things around people's homes. Is there something a test that you'd like me to try?
Btw, the focus seems ok to me, although the sharpness seems better at 1.8 than it did at 1.4 but I just got it so I'm trying not to jump to conclusions
Edit: Ok so I tried taking some photos using the tripod from Beach Camera and I think that it's front focusing? This was shot at f/1.4 and ISO 100, center auto-focus point only, on a tripod with a 2 second delay. I approximated the 45 degree angle by making the height of the sensor the same distance away as the horizontal distance to the focus point (which was 40 inches in this case) I'm using a XS which is an older camera but i don't think should affect the focus. I like the specs on the lens for the price but it has to focus correctly, so I'm thinking of sending the lens with the body to Sigma.
It's front focused in that shot, but make sure you do the tests multiple times, and do it in a bright room to make sure it's seeing the contrast correctly enough to focus properly.
My Sigma 50 misses shots in low light quite often but when it does focus it's on target.