According to the semi scientific results from the TV show Mythbusters computer keyboards have more “nasty” germs than a toilet seat.
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)