So we know there's a spray when the toilet gets flushed, but it's unclear how far it travels and what ends up where.
Ultimately, the problem may be that there hasn't been a peer-reviewed study of toothbrush hygiene. We don't know where the bacteria travel, and we don't know the source of bacteria that may have ended up on the toothbrushes placed in various areas.
"A lot of the droplets that are generated when you flush a toilet, they are too large to spread probably more than a foot or two," said Sattar.
Fecal bacteria means the bacterium E. coli, which is found in fecal matter, among other things. While often used to gross someone out about bacterial contamination, just finding it doesn't mean the germs came from the toilet.
So it's not entirely clear that your toothbrush is showering in your toilet water just because it's nearby. But it may not be a bad idea to put the lid down when you flush.
Fact or Myth? The blowing air from a hand drier in a public restroom spreads germs.
Syed Sattar, a professor emeritus of microbiology at the University of Ottawa, has looked into this issue, and was more than happy to declare it an outdated concern.
"That is certainly a myth, because we have done our own studies in that regard," he said.
Sattar said his team had sampled the air around driers in various public restrooms as people were using them and found no increase in bacteria.
As to the rumor that dust accumulates inside, he said his team had taken apart multiple hand driers in places like bus stations and busy shopping centers and also found nothing.
The real worry about hand driers, said Scott, is having to touch something to start them.
"It's always good to look for systems that don't require you to touch," she said, because the buttons will accumulate germs.
Ideal restrooms, Scott said, wouldn't have doors or handles for the faucet, and would have electronic eyes to start hand driers, faucets and flush mechansms on toilets.
"No-touch is ideal," Scott said.
Fact or Myth? Antibacterial soap keeps your hands cleaner than regular soap.
This myth may stem from a misconception about what we do when we wash our hands. By rinsing in soap and water for at least 20 seconds, we aren't supposed to be killing bacteria, but simply getting germs and viruses off our hands.
"If you can get to a sink and you can wash your hands thoroughly 15 to 20 seconds with regular soap and then rinsing -- that is the most effective method of 'de-germing', or removing germs from your hands," said Scott.
She noted that washing with soap and water doesn't remove all the microbes from our hands, because some are an important part of our skin, and even if we did kill them, they would return.
Given that regular soap and water removes the germs, there is no need for an antibacterial agent, and it probably won't work anyway.
"The speed of action of these ingredients that are added is rather slow, so that they are not there on the hands long enough to present the desired level of reductions," said Sattar.
So the antibacterial agents added to soap, typically triclosan, isn't effective in this case but may present problems, as our next myth explains.
Fact or Myth? Alcohol rubs cause bacterial mutation and help create resistant strains.
Answer: Myth for Alcohol Rubs, Possibly a Fact for Antibacterial Soap