How often do you allow your child to eat cake?

It's fine for kids to eat cake once in a while. It is a sweet indulgence for them and one that almost all kids are fond off. Moreover, how much can you monitor them? No matter how much you keep them away from cake at home, they will end up eating some at a friend's birthday party. I don't think it should be a big problem as long as your child rinses his mouth nicely whenever he eats cake or any other sweet treat :)