Other week in California, I had a UH-60 Blackhawk fly overhead fairly low over my home.

Ran outside to check, and to my amazement it didn't come up as such on globe.adsbexchange.com. The helicopter was showing as a civilian single-engine aircraft, believe it was a Piper or Beechcraft.

That should say something when you see a lot of 'trainers' in certain areas. You never know what they could be now.