Our spam database is mostly fed by users who report spam calls. We process these reports and when we have enough signals for one phone number, we mark it as spam. From this moment on Clever Dialer will warn all users from this number or the calls can be blocked automatically (Clever Dialer PRO). This is why rating numbers is so important.
You cannot only report a number as spam. Why not give the caller a good rating if he delivered good service? 🙂