Well, when it has the Devry or Zenith stickers on it.
Yup, the Devry and Zenith courses used Heathkit test equipment kits, but with the Heathkit logo removed (Most of the time).
I am aware that some courses offered Knightkit gear and of course Conar, which was a clone of some other company, (Or is my memory faulty on the Conar gear)?
Radio Shack offered a tube tester that was a Superior instruments clone, and so did another company or two A model 1000 seems to stick in my mind. Nothing but the lowest end emission tester I had ever seen.( Have one somewhere in the shop. Crusty, dirty, & likely not worth repairing.)