Another case of such a treatement is user Abou Talha that received negative trusts for his avatar. Thought it's true that it is a bit explanatory about the guy, it is nowhere prohibited.
Just Googled it, I cannot believe it. I am already on all the watchlists, but this will create more opportunities for the NSA to spy on me for sure
It seems that the community has found the trust system to be a way to disapprove of unlikeable individuals.