I guess when this tag existed, it would've been put under someone's username after it has been objectively (clear evidence that could be assessed by anyone) determined that the user is a scammer
I have no doubt that it was, however it was only applied by a centralized body with control over most (if not all) the forum. If one of these people suddenly decided to add a SCAMMER tag to someone with no evidence, what could we do against it? (Hint: not much).
so I think personal bias might not be an issue, however, it might be when giving negative feedback.
It may, however this is why the DT system is spread out over several people. If someone trusted left a fake negative feedback calling someone a scammer there would be several ways to combat it. A SCAMMER tag could not be combatted as such.
Personally I do
and I think scammer tag or not, one should always look into the history of the person they're dealing with.
Good. If everyone did that it would likely make a better environment for everyonr to trade in. Sadly, there are some users that like to spread the idea that negative trust = scammer, which makes a worse environment for everyone.
However, this is off topic here, so I won't discuss it further.