It would probably be an even better option to verify that anyone someone is considering leaving negative trust that they are in fact a scammer

I don't think DT member tagged someone without any issue although there might be some exceptions.

(or someone who will likely scam in the future).

A proverb going that Black will take no other hue.

They shouldnt leave a negative rating just because lauda says the are a scammer without evidence.

Most of those have enough reference link. Without reference link, tagging again will look awkward. In this case, DT can check the ref link and tag.