[georgespencer]

It's a great question!

Firstly by taking a bigger sample of references it's more likely we will find commonalities in the negative points.

Secondly we get different perspectives on negative traits. The man you fired who hates you because you were a micromanager is balanced by the woman who was your boss and wanted you to keep close to the person underneath.

Disqualifying things are generally not specific. It's a multiplicity of people saying "do not hire this person."