Deep down, I am convinced a lot of the GTAO populations yearns to be trolled/ owned. It's the only way they can justify their psychopathic behaviour ingame. Which is quite fun to be honest, wtfness is what makes freeroam great.
This is why I have no problem randomly killing players, especially in funny ways. So much talk here of "I only shoot when shot at", well if everybody thought that way nobody would ever shoot anyone and you might as well not buy any guns and ammo. People want to fight in free roam, they just don't want to come off as assholes. Go to passive mode or invite-only if you don't want to fight. The funniest thing is when people say that they'll give others hell if they attack them unprovoked. They want a fight, they just don't want to be the one to start it and then for some reason they feel more honorable.
I like to help players out for like 10 minutes, and then suddenly broken bottle them in the face and drive away as fast as I can.
I use a variety of weapons. Broken bottle is indeed on of my favorites. Another great one is a minigun or auto shotgun from point blank range, and don't stop shooting until you think they've respawned so that they can see their character getting really horribly murdered in the respawn screen.