Dateline - Child Predator Series

I've seen a few episodes of this, and mostly it's horrendous.

The problem I have is that on a couple of occasions, they've lured in guys that were 21, and that clearly seemed mentally young even for 21--like guys who'd never had a girlfriend, etc.

Not making excuses for them, but it somehow doesn't seem quite the same as when you drag in some 45 year old creep who has a pregnant wife at home, and shows up with whip cream and a blow torch.
I'm hesitant to refer to it as "luring" anyone. The predators are the ones who make the first proposition. Sure they're going to get a few that are borderline (such as your 21 year old example), but they're also nailing the 30+ year old creeps in very significant numbers....including the married with children, including doctors, including prosecutors, including those in the ministry in some capacity, etc., etc., etc.

I, for one, am glad they are shedding such a bright light on sexual predators and only wish they had the resources to do even more.