Question might be phrased badly, so a follow-up question would be: "What makes you kill another player in-game?".
We all encounter other players while doing things, some prefer to play friendly or just stick to what they are doing, others go out of their way to kill every player of the opposing faction they encounter. I find it interesting because there's different ways of approaching it. I don't consider this a "do you like world pvp or not?"-kind of question, but rather a scale and where each person draws their line.
Me personally, I consider myself a very friendly player. I might have started fights back in the early days of WoW, but for the last couple of years I stick to my stuff, I don't kill alliance-players I come across, because I have no reason to do so. And if I did, it would just be a waste of time, and I might get revenge coming my way (which would slow me down even more) if I chose to start a fight.
Despite this, like all players I've had my fair share of frustration when being attacked by other players. Usually this comes in tough situations, like me being on a low level alt and getting killed by a 90, or getting jumped by 2-3 players while being alone. When I feel attacked, and when other people start doing shit towards me, that's where my line goes. You could say that I will go out of my way to make that person's life a living hell, which in some situations consists of me corpsecamping them for 40 minutes because they killed me once, without any reason.
As for situations like someone tagging a rare-mob or stealing a mine/herb in front of my nose, I let that slide. If it's a rare-mob I will even help the other player kill it, because I know myself how frustrated I would be if I was killed in that situation. As for other people being killed/ganked, I don't really get involved unless several people witness to being ganked without a reason. If I see an alliance-player attack a horde-player, the horde-player might have started it, so I just don't care enough to help.
I don't want this to become a "world pvp is annoying" or a thread for whining, I'm just really curious how you view world pvp and what ticks you off. Do you just attack everyone when you have the chance, or do you prefer leaving them alone? I have a friend who has a logic that goes: "kill them before they kill you", and that's another approach I've seen with some people.
/Tired, hopefully the post wasn't too sloppy.