Currently, the "Reversal" badge ("Provide an answer of +20 score to a question of -5 score") has been awarded 2 times. I was interested, so I went to see what kind of question/answer pairs these were, only to find out that both have been deleted.
Seeing as both cases where the badge applied have been deemed unfitting for the site, would it not make sense to disable the badge altogether? It fits into the same group as "Tenacious" and "Unsung Hero", which is the group of badges that make sense on SO, but are simply unobtainable by non-cheating means on Arqade.
If the badge is already disabled, this question becomes "why is there still a number of users with the badge if it's disabled?".