experience, judgement, intuition, trust.

good question!

we rarely find such people most of the people want bad things for others even their friends, hurting others is there best hobby they dont care at all they hurt u and be happy for this. im sure that they have no hearts

well if you ask me i rather try to analyse them first.you can see it from them they way they act,speak its hard to say that but in the end of the days you are the one who can answer it. cowboy...

most people are kind, they don't want to hurt anyone. but we should pay attention to someone who will take advantage of being a "kind" person. Love your neighbour, yet pull not down your fence！