And by honor I don't mean the honor-as-currency system that's currently in the game -- I mean a sense of personal honor as in, there are things you make a conscious decision to avoid doing just as a moral gesture.
I thought of this recently after a truly miserable losing streak in Arathi Basin. I wound up in three consecutive matches with a full complement of 15 Alliance players to 7 or 8 Horde (with both sides being PuG's, mind you). Being out-numbered and out-gunned sucks no matter what, but it's made immeasurably worse in places like Arathi Basin and EOTS due to the dwindling number of sites you'll have to rez when your side is being utterly destroyed. There was one particularly awful game where the Alliance decided to see how much honor they could get from us before the inevitable 4 or 5-cap ensuring their victory, and simply zerged us in the graveyard as we rezzed (or tried to). The feeling was made worse by knowing, having also played Alliance in BG's, that Horde would almost certainly have done the same thing had the situation been reversed. PvP is the subject of a lot of emotional dicussion in the WoW community as a result of situations like these, and I think we can all agree that it's not the losses that drive you nuts so much as knowing that the game is full of places and times where no amount of strategy or skill will keep you alive.
There are a lot of things in PvP that I just don't like being a part of.
I don't attack fellow Druids unless I'm attacked first (yeah, I know it sounds crazy, but a surprising number of Druids subscribe to this). I don't join in when an enemy player is obviously being dog-piled. I don't /spit on opposing players or do other rude emotes, and I don't participate in griefing. There's not much about WoW's PvP system that's really all that fair to begin with, especially when compared to games more explicity designed around PvP combat, but in the back of my mind there's still that notion that your opponent should at least have a sporting chance. I risk being called a hopeless carebear for this statement, but I think "honorable kills" are a lot more enjoyable when there's a measure of actual honor involved.