I have an Australian Woma python that I handle frequently and when I got a new albino dwarf reticulated python I was almost positive he got jealous and curled up in his hide for almost a whole month before coming out to play again. Most people say that snakes are not smart enough to feel jealousy but who really knows?
I think most animals are way smarter than we give them credit for, it's just that they don't have the will to do our 'tricks' to evaluate their intelligence. Take for example cats, I think they are much more smarter than dogs, they are just not as willing to do tricks for people. Now take a snake with no arms and no legs who can't do any tricks at all really and may not even have the will to do tricks, how do you judge their intelligence?
I used to have a pet jumping spider that was one of the smartest spiders (and the coolest). I would peer down at him and he would look up at me and tilt his head sideways like he was trying to figure me out. You can't say it's the size of their brain because that spider brain was as small as a grain of sand.
They say reticulated pythons are one of the smartest snakes, my retic will look out the window of his tub and just watch me work in the rodent room. All the other snake will totally ignore me, that retic kind of freaks me out how smart she seems. Some of my rats will just sit and watch me too... Freaky smart.