I don't think they feel affection for anything...including us. I just don't think they're wired to do so.

My reasoning is this: You wouldn't go around intentionally hurting people that you showed affection for unless you were mentally unstable or something like that. If, say, my rainbow boas are doing fine as I'm holding them I might falsely assume that they "like me" but then they almost invariably turn around and latch onto my hand, my arm, or some other body part.

They may tolerate us, but that's the extent of it. I've been a question several times that we've probably all heard a lot: "Why snakes?" (or a variation of it, such as "What's wrong with you???"). One of the things that I love about them is that there is no such thing as a domesticated snake...if you work with them and you screw up or do something that they don't like, you're going to pay for it.

Some are more docile than others obviously, but they haven't been in captivity long enough to be domesticated. If you're working with a snake that tolerates you and you slip up, they'll bite you just as willingly as if you're a large, scary predator in the wild.