You have to be trusted is the only qualifier. The people who are most used for Escrow have been here for years, done dozens of trades and have built up a decent reputation around the forum. Even then, people have abused their position of Escrow and stolen money, so you should still be wary. I don't think there are any official Escrow titles, as that would imply they are endorsed by the forum. Very few escrows are actually needed and all the deals could probably be handled by less than 10 organised people.
Are the identities of these people known? So you know who the real person is? (Social media accounts, phone number etc.)
As far as I know, many people hang out here anonymously. As you said, even people who are 100% safe can make a lot of mistakes for bitcoin.
Escrow are usually members who have proved their integrity by doing various fair trades here.
It is based on a trust system.With time and continuous fair deals the get lots of positive trust (numbers shown in green below their username) making their account valuable.
For example if someone's account is worth 1 btc due to all good rep he has,he would obviously not scam anyone for say 0.5 btc.
This is not to say that he will cheat for more than 1 btc
The point here is that an escrow is safe for an amount his account is worth of.
