If I'm on a PVP server, I generally leave folks alone when I'm trying to get quests done. Unless they run at me. Or target me. Or look at me funny. Or fart. Or make any rude gestures. Or wear pink. Or kill a mob I'm farming. Basically, unless they're groveling at my feet or being overtly friendly, it's on like Donkey Kong. Much as some others have noted, I've been ganked far more often by people I've left alone than people actively coming into the zone to start shit. With the exception of that druid that had the spy account on Mag and would camp our lowbie groups for hours.