I have noticed the same thing. I hunted near a corn field they were picking, a few years ago. And the picker would go right past deer standing in the corn and they would just move over a couple rows. The farmer told me to ride on the picker but that was illegal. He said he always saw deer, turkey, pheasants, etc.. when doing field work.

He used to take his manure spreader and fill it with good pig stuff, and then lay a good coat of that out and around my hay blind. Them deer never knew I was there...