I'm sure I've heard of the plug-in type of air freshener linked with otherwise unexplained deaths in Corns. Too much of any chemical in a room with snakes is always a potential problem - air freshener, cleaners, deodorant, they're all banned from my lounge, "just in case".
Generally speaking, if you spot-clean, you keep smells to a minimum. However, mine have impeccable timing and always dump a load just as I'm expecting visitors - enough time for me to muck out, but not enough time for the fug to clear! I use reptile-safe T-Rex Bio-Fresh, which does the trick. It's nice enough to use round the room as well as inside the vivs.