Is there any scientific merit to the "5 Second Rule"?

washingtonpost.com — Indoor floors are better than outdoors, but grass is better than carpet. The tastier the treat, the longer it can be left on the floor. Cake tastes better than cookies, though, and gets germy before cookies. You can almost never use the five-second rule on cake. Parents will, however, employ it on any foodstuff with a high per-pound price.