There are two sorts of cheating in MMOs. One of them, which is outright hacking the game, is capital-b Bad. Back in the days when Final Fantasy XI was a bigger deal, Fleetool was one of the more popular hacks to the game, resulting in many people getting bans for hacking the game to move faster. That was not all right (the hacking, not the banning).
But then there were the groups who jumped ahead of other groups to get into Dynamis zones. This was definitely not a good thing, and it could be argued that it was cheating; the server community agreed about how to use Dynamis and these players were violating that agreement. But it was cheating entirely based upon a social contract, not an actual one; it was rude and indisputably wrong, but definitely not breaking the specific rules of the game.
I think a lot of our readers have done things like this in the past. Sniping resource nodes in World of Warcraft, intentionally standing in things to make healers work harder in Final Fantasy XIV, things like that. So have you ever done something socially unaccepted in an MMO? Do you feel like you were justified, and do you tend to ignore those social conventions most of the time or usually observe them?