Sounds good to me. Let's let the justice system do it's work instead of engaging is Stasi like behavior. Or no?
And perhaps that is arguable. If that's all they were doing. Instead they take kids to jail by selling them drugs, allowing the seller to sell, or selling them themselves. Alternatively, they are on the other side of the coin - buying "illegal" substances. I'm sorry - but why exactly can you possess or distribute these substances if Joe Sixpack doesn't pass GO and hangs out in a cell for doing the same innate action.
Don't buy it. That isn't American, as far as I am concerned. Governmental agencies should not be allowed to engage in crime or facilitate it. However the type of lackluster response most people give (oh, hard murder.. oh just a "terrorist", or just a "druggie") allows them to more easily facilitate much larger crimes (PRISM? Gun Runner..? List goes on indefinitely) over time. The mentality of "it's for the bad guys" HAS to go.