From
https://bitcointalk.org/index.php?topic=703657.0:
Q: What is Trust and how does it work?A: Trust is Bitcointalk's feedback based on trust (hence the name). The Trust system is made of 2 components: the Trust list and left feedback.
The Trust list is where you select the users whose feedback on other users you trust and how deep is this trust. You can either trust just their feedback (select the Trust depth as 0), theirs and their trusted users feedback (Trust depth 1), and so on (up until Trust depth 3). Trusted feedback will be counted when displayed as numbers to the left of a users post in trade boards such as Marketplace or Goods.
The feedback page is where you can leave feedback on other users or see a detailed view of a users feedback. Trusted feedback will be shown first and untrusted feedback will be hidden by default. You can view it by clicking the link "Show ratings". Last of all, you can see all the feedback the user has left on others.
This covers the basics of the Trust system. If you want a more in depth description of the Trust system and details I probably missed, go here:
https://bitcointalk.org/index.php?topic=211858.0.
Q: Why haven't you banned <insert scammer username here> who is an obvious scammer?
A: Possible (or real, not for me to decide) scams are not moderated to prevent moderator abuse. If we start picking out which ones we call "scammers" and ban, we would make a lot of decisions based on biased opinions.
While DefaultTrust does exist (and is thus considered the standard by quite a few), users are free to substitute or complement their list with other users they trust. That -498 for you is a -2 for me simply due the way I configured my Trust settings as compared to you. Please learn at least a bit of Bitcointalk's history (e.g. now deprecated scammer tags) before passing your uninformed opinion on how the forum should be run.
Then again, you're probably too busy trolling Meta threads to care