Bit of a monster, but scenarios like the following do occur and it's up to moderators to decide how we handle it on a case-by-case basis.
You discover that several well established users have been trading votes for a long time. You confront them but despite overwhelming evidence, only a couple of people admit to doing anything wrong.
Again, these are otherwise valued members of the community. They have answered lots, flagged and reviewed fastidiously, but have, for some reason or other, felt the need
to cheat the systembreak the rules.
So what would you do? You could do nothing. You could wipe this illicit reputation. Ban them. Or do anything else in between. Is there anything that would make you consider more leniency? What message does your action (or lack thereof) send to other, less established users?
I know there isn't a single best answer —and your opinion may change when faced with it in reality— but I'd like to get the measure of the prospective moderators, at least how they feel they'd handle this if it happened today.