I'm extra paranoid when our apartment complex brings in people to spray b/c I keep frogs as well, and they're even more sensitive than my snakes. For what they spray here, if it's being sprayed in a separate room, just stuffing a towel under the door is enough. If your snakes are on floor level, it might be good to put them up on a table or something. If they're spraying the actual room the snakes are in, I'd be wary of bringing my snakes back in same day though.