What makes someone trusted?

donor rank and vouches mainly.

 

Most important is quality and amount of vouches.

The others can all be obtained by someone who should not be trusted.

 

I would say that if a user has donated a large quantity then that at least lowers the chance of them trying to scam for a smaller trade, but looking at feedback from other people who have dealt with the user is equally as important. Altogether I would say a mix of everything

 

It's probably a combination of how well you know the person, how long they've spent on the website, and their trade history.