Digital megger readings for 208VAC/480VAC induction motors and DC motor testing

How can you tell if an induction motor (208VAC or 480VAC) is good or bad by using a digital megger?  Can you use a digital megger to test DC motors as well?  If so how can you tell if it's good or bad?

A megger has a specific purpose, to test for insulation breakdown between windings and the motor stator or frame. Normally you just tie the phases, or phase and neutral together, and measure between them and the motor stator or frame. Additionally, In the low ohms range it will test the quality of the bonding between the ground lead and the frame, and it will also test the continuity of the windings.
Search on"megger testing of motors", for example,
https://www.instrumart.com/assets/Megger-insulationtester.pdf
This article gives some indicators for acceptable insulation resistance values
cheers,
Richard