Even experienced ex military CFI can struggle in civilian teaching as there is a far greater spread of individual needs among the candidates. And the lower level of progression can frustrate them into being overbearing and sometimes irate at students, just like ex airline pilots who expect new ppl prospectives to progress like a new FO converting to type.
As said above, experience helps with the bag of tricks, but a good instructor is a good instructor, irrespective of background. The good instructor will only become better as they gain experience and hopefully have good guidance from an equally good mentor. I've met some great pilots in many different areas of aviation, most of them would make average instructors and some with awesome stick and rudder skills have been, or would make horrible instructors due to their lack of interpersonal skills. I've seen trainees give up because their instructor/trainer was so bad, some have been able to come back later with another person and kick on and realize the dream. Others leave forever shaken by the experience enough to not come back.
So if you want to instruct have at it, but don't do it for hour building, do it for the experience. And make sure you learn as much or more than the students as you go, then when you finish up instructing you will be a much better pilot for it.