The amount of information that can be inferred, especially when coupled with more data from other "brokers", is crazy. You might be flagged as a depressed person if you skip brushing some/most days. The time you wake up and go to work might be an indication of your social status, together with how often you replace the head.

You see, they'll sell this information to your health insurance company, so that your premium will increase if they think you brush too seldom or not thoroughly enough.