What I've found is that I am a quester/gatherer (a newer modification of the hunter/gatherer for the 21st century) and tend not to attack someone unless they bother me. I am also a very bad PVPer so tend to never win those battles.

However, since Cata released there have been several times where some flagged Horde player was killing an Alliance member near me and I did step in and lend a hand and kill them. They came back later while I was still flagged and tried to attack me, but I put them down a second time, so then they never came back.

But, I value my time, it's why I left a PVP server long ago. If I'm questing or gathering, I like to take breaks to get food, drink, whatever, so go afk quite often. I never liked coming back and finding myself dead.