--snip--
1. If someone gives you a negative trust, can you fight back like proving yourself correct and removing the negative trust from your profile.
2. what advantage you get if you give someone a negative trust?
1. Yes you can, given the fact that you are actually correct and not just trolling, have complete evidence to support yourself. Being calm and patient is one other way to have that negative trust removed because you'll need patience rather than just fighting alone.
2. You won't get any advantage as your rating will only be seen to you (like when you will visit their profile and they have 0 negative ratings, it will start showing -
1 to you, but to you only and not anybody else except if someone has kept you in their trust list). Other advantage is, you'll stay aware of the fact that either you don't trust that person or have some issues with them (I don't know what, but I've seen strange reasons from people while tagging some users).
there are scammers that gives negative feedback, like bob123
What made you say that about Bob123?
He had been one of the most active people in terms of spambusting, scambusting as well as possess great technical knowledge and many people (including me) on this forum are inspired by him. Do you have a single evidence to prove your words?