There's actually a pretty thriving "snitch culture" in some prisons. For example in the case of David Brown, one of the guys who cozied up to him in prison was a well-known snitch who tipped off the guards about a couple of things he said (people like Brown tend to have narcissistic personalities, and as such they tend to not think that what happens to others could happen to them).

So yeah, it can be pretty common to put a newbie in with the "snitch" and see if anything comes up.