All you really have to do is read.
When someone makes a good, safe trade, they will reply in a post "smooth trade, thanks" etc etc
Go to someone's stratics page, look at the people that have visited the page, PM or ICQ them to ask their opinion of the person in question.
<------------ CLICK ON THEIR NAME
Last, but certainly not least, when visiting the person Stratics "homepage", go to the tab that says "Statistics". Under this tab, there are two options:
"Find all posts by Slickjack"
"Find all Threads started by Slickjack"
READ READ READ.
This is the NUMBER ONE way to quickly ascertain who and what a player is and if they can be trusted.
PROOF IS IN THE PUDDING.
It takes years to gain a good reputation, and ONE BAD TRADE (or theft) to lose it.