It is hard to define the difference between chatbot and normal chat in script. You could find some points that are obvious, but even those can also turn out mistaken.
My example is if you make a blocker that bans people for saying a message with someones name as they join. My situation is if you invite someone to the server using some other method like the IRC or an IM. You might say "*name* is coming" as the person actually joins, and get banned.