Many objects that people touch every day are dirtier than a toilet seat.
confirmed
Adam and Jamie chose a total of 8 objects to test for cleanliness: toilet seat, money, kitchen sponge, hotel room remote, computer keyboard, light switch, cell phone, and shopping cart. They swabbed each surface for 10 seconds and created Petri dishes from the swabs that incubated overnight. Their first method of measurement was to count the number of microorganism colonies on each dish. They found that the toilet seat sample actually had the fewest colonies, while the kitchen sponge sample had more than they could count:
kitchen sponge (most colonies)
money
light switch
computer keyboard
hotel remote
shopping cart
cell phone
toilet seat (fewest colonies)
However, they always wanted to account for the nastiness or harmfulness of the types of organisms on each Petri dish, so they had a microbiologist re-rank the samples. The list was as follows.
kitchen sponge (most nasty)
money
light switch
computer keyboard
toilet seat
cell phone
shopping cart
hotel remote (least nasty)
Finally, Adam and Jamie decided they needed a larger sample size to provide better results. They enlisted a group of biology students at UC Berkeley to collect more samples from the top five dirtiest surfaces. After collecting and analyzing these samples, the final list was as follows.
kitchen sponge (most dirty)
money
computer keyboard
toilet seat
light switch (least dirty)