My cat watches my snakes when they're in their enclosure. The worst thing that happens is my cat jumps up on her shelf where she watches and scares the daylights out of my timid BP if he's out of his hide, haha. But other than that, I've had no problems. My snake has been on me while my cat is out and my cat will sniff and walk away. She knows the smell by now. And my snakes know her smell. There are no issues between the two.

Now my cat and my leopard gecko? Different story! My cat definitely wants to play with my leopard gecko when he's out, hahaha