It really is hit or miss so to speak. I've done both. I have literally had a 2&1/2 yr old 8pt come and mount my doe decoy during the rut, and ive had bucks come from a ways off just at some grunts and them seeing the buck decoy. But, ive had equal amount of times where a buck will look at the buck(or doe) decoy, hear the grunts and pay no mind... I dont see why it would Scare any bucks necessarily. Most of my hunts are without a decoy and grunting/rattling can get a LOT of reaction. I say Give it a shot!