That's because, most of the time, a keyboard/mouse will NEVER be cleaned (and desks themselves something like twice a year) while toilet seats will be cleaned quite often, even more than once per day in a big enough office.
I clean my keyboard and mouse regularly, as well as try to keep my hands clean while I'm working (if I eat a chocolate, I'll wash my hands afterwards, for example), but I know I'm the exception.
Great question. To be honest, when I was doing my research I was able to come across multiple quotations of a study talking about these numbers. However, attempts to actually find a copy of the study in question led me to two different dead links. It's why I didn't bring it up in my blog post. I simply couldn't find a copy of the source; as compelling as a statement regarding toilet seats may be.
I hate that it's so hard to find a copy of an academic study.
Should you a find a copy of the study that explored and expounded upon this, I would love to see a link.
I clean my keyboard and mouse regularly, as well as try to keep my hands clean while I'm working (if I eat a chocolate, I'll wash my hands afterwards, for example), but I know I'm the exception.