I have been telling ya'll for sometime that referring to politicians as snake, weasel, etc. is simply an insult to the animal. It's also giving credit to the politician for being better than what he/she is, the lowest form of life on God's green earth. Fortunately animals aren't able to know they are being insulted.
Being more serious now, I've always wondered about why animals are viewed the way they are by us. A lion kills and eats other animals and is held in high regard and referred to as the King of predators. Snakes do exactly the same thing and mostly to animals that are considered pests but are hated and feared by most people.