Im sure the snake brain is mostly fight or flight, eat, and breed, they dont possess higher intelligence as their brains are mostly brainstem which is mainly instinct and body functioning. Mostly all animals can be conditioned in some manner with either classical or operant conditioning techniques, this however does not denote intellegence by any human standard only that they can make associations. It seems that people get emotionally attatched to their pets (as they should) and like to believe they possess human qualities and attribute them to their snakes where there are none. Snakes indeed do have their own personalities and some are ahead of the curve compared to others but thats about as far as it goes.