I used to be that way before the mental state feature. Now I shoot all red dots on sight. Chances are you didn't get red from NOT shooting people on sight, so I have to assume you're a douchebag about to perform some douchebaggery, and take preventative action.
I'm a red dot. Became that way by acting in self defence against all the paranoid little white dots, who literally shoot everything, or just drive around on their own and then sh*t themselves when a player comes nearby.
When I do try to be friendly, it backfires on me. Me and a friend were sat outside Eclipse, just next to the garage door, pretty much hugging the wall because some idiot was pursuing us, and was camping on the roof with a Buzzard and a sniper rifle. Some twat comes out of his garage in a vomit-inducing Elegy, and I give him a friendly honk of the horn. He crosses the road in his Elegy, but then changes his mind and gets out, and comes over to us. I put my gun away to signify friendliness, as does he. 5 seconds later his auto-shotty comes up, and as I tap L1, he kills me. Little twat then shoots my friend, climbs in his Elegy and speeds off. I went to pursue him but then he left the game.