Encarta Dictionary defines aggressive as: Likely to harm; showing a readiness or having a tendency to attack or do harm to others. I think that was the initial idea behind this post. Chondro, I honestly don't know where you are coming from here. Yes, snakes in general do not bite to be mean, there is usually an alterial motive behind it--feeding, defense, etc. BUT, if someone asks you what is the difference between a ball python and a african rock, it does not take a rocket scientist to see that you are less likely to get bit by the ball python. This is the same in just about all of God's creatures. If you go out into the woods and start picking up animals, some will bite you, while others will not. So what is the difference? ALL wild caught animals will react differently to human interaction--do they all feel threatened? Yes. Will they all bite? No. This is the whole basis behind the question of this post. Some are more apt to bite, others are not. This is what makes certain animals AGGRESSIVE and others not. Read the ditionary definition again--those that show a tendency to attack. Would you get the same reaction if you tried to pick up a wild boar as you would a wild salamander? Of course not. That is because one is more aggressive than the other.
You also stated that "If snakes can love, then they can't hate and if they can't hate then they can't get angry." But then you go on to say that "animals have instincts, not feelings." Sounds to me to be a contradiction. The act of love or hate is a feeling, not just an instinct. The real question should be, do snakes have feelings? I believe they do, just as they have instincts as well. To say that there is no such thing as an aggressive snake, in my opinion, is incorrect. Certain animals(snakes) have certain reactions to certain situations. Some react with aggression, others do not.
As seen on a bumper sticker--"My snake ATE your honor roll student"