Having some measure of experience with rats, I offer these observations. I have no personal information on a single exception to the following, for what that’s worth:
-Any member that has a felony conviction, especially a federal conviction, will eventually be pressured into ratting. Never allow them in. Even if they are off of parole/supervision.
-Any member that has a family member convicted of a federal crime, will eventually be pressured into ratting. Never let them in.
-If you know the person is doing something “shady,” especially tax evasion or drugs, they will eventually be pressured into ratting. Never let them in.
-All informants must produce results. They can’t just observe and report. Beware of any new member who makes suggestions to do anything.
-Background checks are useless against federal rats. Local rats, maybe.
-Rats need audio at the federal level so they have to record their conversations with you.
Finally, your paranoia can exceed the ability of a rat and the documentaries “If A Tree Falls” and “Better this World” are training films for counter-intelligence.