What does Tolson means when he say, "Black is always equated with failure"

Words meaning failure are connected to the words meaning black--he is explaining how even the language is set to expect failure from blacks.

This quote is from Great Debaters and Tolson is speaking to the students that didn't make the debate team. He lists words meaning failure that have a root word connected to the word "Negro". He follows by stating they should make their own dictionary--meaning they need to not let expectations stop them from being successful.