Proper bathroom etiquette varies based on the setting. In a home, for example, it's probably a good idea to light a match in addition to a courtesy flush or two. This will get rid of any lingering smell. Of course, this will only work if there is a matchbook handy.
Hosts who want their guests to practice common civility in the washroom can go a long way in making it happen by ensuring that the place is well stocked. That means plenty of soap, hand towels and toilet paper (at least one extra roll). It also means keeping a plunger nearby [source: Ahlberg].
If you're entertaining, you may also want to leave a note near the toilet that alerts users to any equipment issues. That includes strange flushing requirements – hold the handle down until the bowl clears, jiggle it a few times before flushing, stand on your head and count to 10 before using – that your guests should be aware of. If you don't want to recreate the toilet scene from "Dumb and Dumber," make it very clear to guests that a toilet is out of commission and direct them to the nearest alternative.