I've had good luck in the fog, but I admit it can be nerve wracking if you are hunting a place like Kodiak with big brownies in the area and you pass salmon carcasses and scat on your way up the mt. LOL
The first pic is a foggy day hunting on Hawkins Island in Prince William Sound. We get up to where we know there are deer and sit on a good overlook. The deer seem to think they are still feeding in the dark and wander about. Right when the fog lifts is the prime time to see something. My buddy got a small fork horn that day. 2nd pic
The third photo is a couple nice 3 points my buddy, on the left, and I got on Kodiak back in the 80s. It was so foggy we'd have never made it up the Mt, but we had a ridge we always followed which got us to the top. I'd planted my buddy on a good spot and was going up the ridge line when a doe took off from less than 20 yards. Then my buck came out of the fog and I shot him at about the same distance. My buddy came over to see what I'd shot then slowly headed on back on the main ridge and found his laying in it's bed. He shot it at about 10 yards. You can see the remnants of the fog that lifted after we got the two bucks together for a picture and dragging them down to the road a couple miles below.