No they don't smile for me.
I look at how stressed they seem to be. My snakes are tense, jumpy and other things of the like when stressed, often going into a defensive posture.
I "say" that my snakes aren't stressed when they are active and seemingly curious. Seeking to look out the new things around them, smelling the air, etc.
That's how I define when my snake seems happy or pissed. So no I don't hear my snake tell me: "this is so cool mom, thank for taking me out!" or "mom! I don't want to go out!" but I think that from how I "read" my snakes that I am picking up fairly good on their "mood".
Keeper of 5 snakes, leopard geckos, 1 green iguana, 20+ tarantulas, 2 dogs & a bunch of rats!