From what I've read on the subject (this particular topic having sparked a very heated fight between my fiancee and I) it seems that it's at best risky to use any air carried products in the room with your snakes. No candles, no incense, no air fresheners, no cleaning fumes. There certainly isn't information to say that it's helpful, so we just avoid it. But, then again, if your room is big enough and it's airy enough, it's probably not going to kill them.