It's more technical than unethical. You can't expect thousands of servers to all stop serving your ads the microsecond your balance runs out. Nor is it reasonab

It's more technical than unethical. You can't expect thousands of servers to all stop serving your ads the microsecond your balance runs out. Nor is it reasonable to expect the costs of the ad impressions to be an exact multiple of your budget. You may wish that Google would eat the cost, or average things out, or whatever. They have decided not to, just as your phone company decides to round up your minutes. Nothing to get too irked about.