Bitcointalkforum is not some savagery platform. When it got to do with things of trust ratings and even at times, other accusations that needs to be proven, it gives you that chance of defense to clear your user to be of reputable character.  When you are tagged out of suspicion, you can either create an appeal thread, appeal to the DT who might have tagged you or possibly right your wrongs and the DT whom might have tagged you might consider withdrawing his or her tagging of your account.

Talking about advantage, it doesn't have to help him or her in per say but, it in turn helps you and other users of the forum. The DT have found a flaw for which, he or she is not likely to play into but other users might and as such, he or she chooses to caution you on how to act when dealing with such user and as such, preventing the inevitable should it be true.