I think there's quite a few who use the DT system incorrectly, likely including myself at times. Some use feedback as a notepad, some use it as a weapon, some use it to control, and some use it only for trades. A decent number of the people on DT have no idea how to use it and there's also a few that look to join ranks(DT gang) and use the system in a corrupt way(I have no proof per say, just my feeling on a few members).
I think we give too much respect to scam busters and people who find alts in the past. Most of the time they did a good job, but over time the quality of their tags went downhill. I'm talking overall, not just any one specific user.
Without a reputation system many started tagging scammers, spammers, and account sellers making lines become blurred. Honestly, if users are engaging in what some consider "shady" activities, they prob aren't really to be trusted in a trade. Is the system perfect, no but it's what we have.
If you have a suggestion of how to make the system better, by all means share it with us.