Web of Trust (WoT) is a really hard concept to communicate. 

I've been thinking about it a lot and trying to design something that most people can understand, and frankly there's no easy solution. 

The best thing people can understand is a word. A label. 

This is why I think the best thing to do is just to show how many people that you follow, also follow the person you're looking at. 

And if you already follow that person, show an icon to indicate as much. Even this icon will be confusing to some people, but people will get used to the meaning. 

Numbered scores, colors, or anything else we decide to use will only be misinterpreted. 

Ultimately, I think WoT indicators other than a textual label are going to do harm to the user's perception of someone else, or to the person who sees that they are not an ideal number or color on someone else's screen. 

People are not numbers or good / bad colors. We should probably never try to categorize ourselves as such.