Turkeys in the fall have a totally different mind set then they do in the spring.
I have walked under them in the fall with blaze orange on, and had them just putt at me while still staying on the limb.
While in the spring, moving to my spot in the dark, (quietly) in full camo,take off from the thier roost.

Idon't know exactly what it is, but they are definetly a different bird when spring rolls around. Try moving like that in the spring, and you will get busted FAST, and they will be gone quick.