Not that I would mistake them for a deer but that they could be in the line of fire and I would not know it.
Bottom line is that they are the ones taking the risk. Hunt hard, know what you are shooting at, and be aware of what is behind your target. You could not be expected to do more.
FYI: I wear a solid blaze orange vest and cap whenever I hunt, whether or not the state requires it. It doesn't spook game!