Has an AFL game ever ended 98-78?
Exactly once. On July 29, 1944, Essendon beat Melbourne 98-78, and no AFL game before or since has ended that way. When it happened it was a scorigami, the first 98-78 in league history.
That makes 98-78 the 3836th most common final score out of 6,607 that have ever occurred in AFL. One point away, 99-78 has happened 4 times and 98-79 has happened 11 times.