I have used a grunt call for years. I stand hunt. I have had numerous bucks respond to it by walking in my direction or they try to circle me it seems. I have never heard them grunt back. Does, and fawns with does, I have had the opposite happen. It seems that once they hear it, they get nervous, and walk away briskly into thick cover.
Kinda off the subject, but I have had does and fawns walk a few feet away from a scent wick and not even bat an eye, as if it wasn't even there. I used it one season, and didn't see any bucks that year.