I suppose I would be considered to be one of those "old timers"...as much as I hate to admit it.
Personally, I don't discern between gobbles other than whether I can tell he's coming, going, or staying put. I've had tom's gobble a lot to my calling and go the other way hastily (kindly referred to a "runners" rather than what we would like to call them)...or just hold their ground. Then again, I have had gobblers show very little interest, but eventually wander over to me...if I didn't screw things up somehow (which is always a possibility)
In all cases, my ultimate goal is to determine which of those three things the gobbler is going to do...and adjust my own course of action based on that. Generally, it becomes pretty clear within a short period of time what kind of gobbler I am dealing with just based on the amount of gobbling and the location changes (or not).
I think some of the things we all experience in our hunting are what we call "courtesy gobbles"...which are usually single gobbles (or perhaps a couple) in response to our calling from a gobbler that has absolutely no intention of giving you the time of day regardless of what you do. Often those gobbles are from somewhere high on a ridge or through a jungle of impenetrable "crap", the purpose of which is for you to expend your time and energy to go there...only to have that gobbler never open his mouth again...or show up if you have the patience to sit there for an interminable amount of time and wait for him to come.
Of course, some gobblers are going to be more cooperative in letting you know their intentions than others. I have found that a lot of gobbling that is steadily getting closer makes me somewhat optimistic about the potential outcome.