Bathrooms: you poop in them, and therefore sometimes they smell like poop. There's no real getting around it, unless you want to install some sort of industrial-grade carbon-filtered fan system, which would probably work but honestly? It's poop. We all make it, and it's not like a stinky bathroom is a surprise. (How dare this place where people poop smell like poop?!)
That said, there are a few common sense ways to make your bathroom stink less after its gotten a fecal workout. Stop snickering for a couple seconds, and let's talk about it.
So, of course you should make use of all technology available to you: turn on a fan and open a window. Yes, duh. But there are a couple other things too.
Flushing toilets are an awesome joy of modern life, but their method of swirling the water around actually sends a misty geyser of water (AND POO!) into the air. Here's a choice quote from a guy named Charles Gerba, PhD, a professor of microbiology at University of Arizona in Tucson: "Polluted water vapor erupts out of the flushing toilet bowl and it can take several hours for these particles to finally settle — not to mention where."
I'm not a germphobe at all, so I'm actually not worried about where the particles might finally settle, but I do hate the smell of poop, and those "polluted water vapors" smell like poop. So regardless of how you feel about germs, shutting the toilet bowl can minimize poop smells. Heck, you can even flush the toilet while still sitting down, using your own body to prevent the poop air from circulating. (Although your butt may get wet.)
The ol' "light a match" trick
It's an old trick for a reason, but you can make it a little more snazzy by having your own DIY matchbooks on the back of the toilet.
Excuse to clean!
If the bathroom smells particularly bad, use the odor as an excuse to do a couple minutes of cleaning. Take out your cleaning product of choice and take literally two minutes to wipe down the bathroom sink, or clean the bathroom mirror. By the time you're done, the bathroom will smell as much like clean sink as it does like poop … which is better than just smelling like poop.
Surely you've got a trick you've learned that we've missed. Don't leave us in the stink! What's your freshest-smelling idea?