Honestly I don't reach into any enclosure, ever.. aside from ball pythons in a rack. Like, I don't even reach into a corn snake's enclosure. Lol
Maybe I just suck at noticing the signs, but every bigger snake (aside from the real giants) that I've had to work with seem to just suddenly lunge into motion if they're going to bite. It's like they're just staring, no posture or anthing, and I just won't reach in there, I just always wonder. I've seen enough snakes fly back when they're looking away to not want to grab them even when they aren't even looking at me.
I had a woma slowly come out of its bin once, I had my foot up on the bin as I was standing there talking to someone, he came up ever so slowly, rested his nose on my knee, and then just opened up! LOL
Love snakes, hate their teeth!