The way I see it now, there is no clear official guidelines for leaving feedback (which I think there sort of should)
I share this opinion that there should at least be a guide of what deserves a tag and what does not. The cases I've observed has been very broad, from possible scams to low quality post. Users can get tagged for whatever reason depending on the discretion of the one leaving the feedback.
I have also come across a situation where a user was red tagged for possible pliagarism whilst the account was not banned.