Been wondering this for a while.
I've seen orange negative with black positive at the same time and wondered why it wasn't just red??
Because someone can have trusted trust rating while having received negative trust as well. The color used for that is orange instead of the red text and you won't see the red "Trade with extreme caution!" either.
Hey thanks for the info - I'm still reading up on the trust/s - still working out the
????
one, it seems to have cropped up amongst some of the trusted inner circle in the last few days...

I believe it happens when someone with 2 or more positive rating get a negative rating*. it will change if that person get a positive or negative rating.
*the negative rating have to be new.