In general the question is what would happen (and why) if a 220V motor was powered by 110V. Not interested in the conversion wiring, say someone made a mistake and wired a 220v motor using 110V. My opinion is it would run slow, if at all, and eventually fail. Is this correct?

Slow und under powered. Most of the time if you lose a leg ( dropping voltage on one side ) of a 3 phase motor it will still run but not have near the power.

The motor could burnt... sinngle phase