Has an AFL game ever ended 86-31?
Exactly once. On June 19, 2016, Sydney beat Melbourne 86-31, and no AFL game before or since has ended that way. When it happened it was a scorigami, the first 86-31 in league history.
That makes 86-31 the 3836th most common final score out of 6,607 that have ever occurred in AFL. One point away, 87-31 has happened 1 times and 86-32 has happened 2 times.