I personally think that all animals have feelings and moods. My dogs definitely have feelings and moods, my horses did, my guinea pigs did and even my betta fish did when I raised them. What's to say snakes don't? I think it's all a matter of spending enough time with an animal to notice even the slightest differences in behavior. I know that I have a snake that apparently hated her previous owner. He warned me she was pissy and struck and bit but when I got her she's been the sweetest little thing!

Just like we can sense people we don't like I'm sure animals can sense it too.