Bobgobble makes a good point here:
Sure many guys have snuck up on a bird or two and got the drop on them but to make a habit out stalking as your primary means to to turkey hunting will for the most part result in spooked birds,which makes for running and flying shots,which results in wounded birds!!Besides this sooner or later you will run into somebody else doing the same thing which no question results in a dangerous situation.
However, sometimes you get the chance to use this maneuver--I think we all have but, in my opinion, I do not think it' s unethical. Just be careful other hunters aren' t around. They might be trying the same maneuver. Put this consideration on your " mental checklist" before you start the stalk and I think you' ll be fine.