I have seen deer in much closer quarters to me while in fog. Perhaps that is in part due to not being able to see further into the fog and therefore the only deer seen were in close quarters than is usual. I like stand hunting in fog when I know exactly where I am. Otherwise orientation is all messed up and safety goes with orientation.
It becomes easier in fog to better understand how scent gets carried to game (in all weather conditions). As the tiny water droplets that comprises the fog drift by us (you can see them) they pick up our scent from static items like hair, clothing, shoes, sweat, hat and watch bands, and dynamic items like breathing, blinking, skin chaffing, etc. and carry it all down wind. Even when it isn't foggy, similar water droplets are still present in the air.