RE: Bucks Grunting?
Bucks (and sometimes does) use grunts as a normal means of communicating with each other. They don't do it constantly as a rule except when the rut is on and they are trailing does. Then, it is common to see a buck with his nose to the ground constantly grunting as he trials a doe. I too have seen lots of deer on many occasions that were as quiet as a church mouse, so I'd question the part about your friends "always" hearing bucks grunt. It's possible it could be something else, but I doubt it. I too have been with hunters that "always" come back to camp with stories about hearing a buck grunt, but I normally blow them off when I consider the source as they tend to exaggerate on everything they do and say anyway.