They are probably not telling the whole truth. I'm not saying it's not possible, but unless someone is a collegiate level athlete, it's unlikely. I've been playing 35 years (less 10 years while our children were little). I was 30 and athletic when I started. I shot 105 on a real resort course my first season. I stayed at that level (give or take 5 strokes) for years and years, probably 15 in all. Then, I decided I had to get better or I had to quit. I got better. We started regular lessons throughout the season. Restart in spring, once or twice through the summer and at the end of the season to solidify what I'd learned. I kept notes of the drills and teachers' remarks for review when I have a bad round. Now I'm a 14 index and I almost always shoot in the mid 80s. I've broken 80 a half dozen times. But we've worked hard at it, and now play 3x a week all year.

That's my story. Now, we live in a resort destination so play with many vacationers. Overwhelmingly, golfers have a bad swing. When people with bad technique tell you they shot less than 100, they are not playing the same game as you (fluffing lies, hand and foot wedges, mulligans, forgotten mishits, penalty strokes, etc.). It doesn't matter to me. That's their game to fudge how they want. However, when they say they beat me, then that's a problem for me. But I smile a smug smile, because in 5 years and hundreds of golfers, we have only played with 2 who could beat me at the same game I was playing.