Trust rating system is not moderated but people who spam the system will be banned. Otherwise people figure out negative ratings with communication.
Where do you get this knowledge? Do you have 1 single example?
Its not like spamming trust is not a topic in meta allready
https://bitcointalk.org/index.php?topic=558001.0Trust spam isn't allowed. If I see anyone posting dozens of fake trust ratings (from one account or many alt accounts), I will delete all of their ratings. But Inaba is hiring multiple people to create these ratings. It is impossible for me to determine whether these ratings are "real" or not, so I'm not going to delete them. (Obviously all negative ratings are very likely to be fake, but I'm not going to guess about this.)
I agree that it is a little annoying to see a wall of negative ratings, but this is in the "untrusted" section. The way things are set up currently, untrusted ratings can be easily spammed in a number of ways. That's why those ratings are hidden by default.
Yes, but leaving negative feedback on accounts that are being bought/sold wont fall under spam unless they are dishing out hundreds for no reason. I'm almost certain if someone left you negative for this theymos wouldn't remove it.