I think some of it is an "active, hunting snake" thing. I've noticed curiosity and facial recognition in both of my more active snakes. Well, okay, less curiosity on the part of my garter, but they're so small it's not surprising they're more nervous than curious. The Russian is SUPER curious--anything new in her enclosure gets instantly investigated, and people are GREAT to stare at.
Womas sound enjoyable, but I'm not sure about their love for tasting things.