Has an AFL game ever ended 72-20?
Exactly once. On May 2, 1903, Geelong beat St Kilda 72-20, and no AFL game before or since has ended that way. When it happened it was a scorigami, the first 72-20 in league history.
That makes 72-20 the 3836th most common final score out of 6,607 that have ever occurred in AFL. One point away, 73-20 has happened 1 times and 72-21 has happened 1 times.