I'm not abusing the system, I'm just using it.
Here you are on https://bitcointalk.org/index.php?action=trust . So basically all members are trusting you and all will see my feedback and not your feedback. This is fair system right?
Basically, people who branch off of someone who branches off of DefaultTrust need to be much more conservative with their ratings than other people because of the fact that the feedback is trusted by default. This usually means that if you weren't involved in a scam, you must have solid proof that a scam took place before leaving feedback. If you don't branch off of someone who branches off of DefaultTrust, you are free to use the system however you want and convince people to trust you.