A good friend waited on a little knob on a cold snowy day. The rest of us was pushing an adjacent area of thickets towards him. Many deer broke in front in the thickets. We knew they would funnel toward the knob. We were hunting does or bucks and expected to hear a shot.
No shot.
When we got there my friend told the sad tale of a beautiful buck slowly wending it’s way toward a clearing. He sat there with his scopes rifleup near his face waiting. When the deer broke into a clearing he brought his gun up to see nothing. He had been breathing directly on the lens and the outside was fogged. He quickly tried to rub the fog off with his sleeve but made too much movement which spooked the deer into a run.
I have a friend who bags his limit every year using open iron sights on an O3A3. Scopes are over used and over rated. Just have some patience.