How is it decided that a dean has failed? Is it by displeasing the faculty, or the upper admin?
We have a dean who is known as a hothead, who yells at anyone who doesn't go along with his act and ideas, chooses favourites, keeps secrets to help implement a "divide and conquer" policy, ignores e-mails from faculty members, regularly violates the rules of the union contract, and spends more time off campus than on. There are still a few people who are fooled by the facade and talks about "how much he cares about us all" (yeah, until you inadvertently end up on the wrong side!) and "how much he's done for our department" (while crushing others), but most people are constantly disgusted.
And yet, this is not considered a failed dean. Very obviously, anything short of running an actual brothel out of the faculty lounge is acceptable.
I know this guy! You and I must have worked together at some point since 2005.