I often leave negative trust feedback for scammers before they scam anyone, or after they scam others. I don't often get scammed myself.
Perhaps the wording next to "negative" should be changed from "I was scammed" to "this person isn't trustworthy".
Sounds like a fair suggestion in my opinion since its a good change in wording.
It's possible for people to be suspicious from the start and it doesn't hurt to be proactive in preventing fraud since it's not always "I was scammed" but I am preventing people from scamming / their intentions are suspicious to me.