The problem isn't as bad with coins, largely because the metals -- particularly nickel -- often kill many of the bacteria.
The next time you sit down for a late-night movie at home, you may want to keep your hand out of the popcorn bowl if you've been handling the remote.
People are constantly handling their remote controls -- and, as Gerba points out, nobody ever disinfects them.
No wonder, then, that it is often the dirtiest object in a hotel room.
Tierno recommends wiping it down at least once a week, and more often if someone who is sick handles it.
Gerba points out that sickness will make the remote even worse, because people who have a cold or the flu tend to "jump in bed with the remote control and contaminate it."
The Laundromat is hardly a bower of cleanliness, but even laundry done at home is rife with germs.
There is about 0.1 gram of fecal material in a piece of underwear, Gerba said. That amounts to approximately 100 million E. coli bacteria in an average undergarment load.
Unfortunately, only 5 percent of people use very hot water to wash their clothes and then dry them for a full 45 minutes, a process Gerba said would kill more bacteria. Skipping these steps means that transferring wet clothing into a dryer leaves a film of germs all over your hands.
To minimize exposure to harmful bacteria, Gerba recommends doing laundry that requires bleach as a first load to disinfect the machines and saving undergarments for a final load. He also cautions against using the same sorting tables for clean and dirty laundry since the E. coli from the dirty clothes will transfer to the table and then back onto your freshly laundered clothes.
"Your clothes are a lot germier than they were 50 years ago," Gerba said. "Never kiss anyone who has just done laundry for you."
You may be better off preparing your food on another surface.
According to Gerba, there are 200 times more fecal bacteria on a cutting board than a toilet seat.
The reason, he explained, is that many people rinse off their cutting board rather than thoroughly washing it.
"You have potential pathogens when you're dealing with food," said Tierno.
He recommended preparing a solution of a quart of water and "a jigger of bleach" and then wiping down food preparation surfaces before making anything on those areas of the kitchen.
The telephone provides a convenient meeting place for two different sources of germs -- your hands and your mouth.
After all, as Tierno, pointed out, "People are the source of most of the germs."
These germs are not just from your hands, but sources like your saliva as well -- which is why the mouthpiece is often even dirtier than the handle.
And again, it's not a device people clean too often, which is why both land lines and mobile phones present a problem.
A study done in Israel last year showed that 20 percent of hospital workers' cell phones had some form of harmful bacteria on them.
The moist surface area on the average water fountain is an ideal breeding ground for bacteria and viruses.
"Everybody who has a cold or diarrhea has to drink a lot of water," Gerba said. "The sick people hang around here."
In fact, research has shown that water fountain spigots often have twice the amount of bacteria as a toilet seat, more than 2,000 microbes on a water fountain compared to less than 1,000 microbes on an average toilet seat.