Checking some of the recent winners of the Mortarboard badge, I just found three which got the badge as result of serial upvoting. One. Two. Three. (All of them have "Serial upvoting reversed" day after gaining the badge)
I am aware that sometimes it's innocent, e.g. upvote troll who just enjoy wracking havoc, but there also obvious cases of gaming the system like this one who created a sock puppet account to gain the badge and is now suspended for it while still keeping the badge.
Innocent or malicious, those users shouldn't keep the badge.
I know the current policy says "Once you earn a badge it's yours" and I know that devs can revoke badges manually, but at least for this specific badge manual removal would just take time and efforts.
The change I propose is that after "Serial upvoting reversed" happens, it will also check if that user got Mortarboard badge in the same time of the serial upvoting and if so, the badge will be automatically removed.
More than that: to prevent the malicious type from simply trying again, flag will be raised when such thing happens more than once and moderator will be able to suspend the user if he can confirm it's sockpuppet activity.
Just found another one, the most recent winner of the badge. :D
On a wild guess, if such script will run on all existing Mortarboard badges I fear their amount will be cut in half.