I've noticed the cops thread, and thought a few things might be helpful. The first is that a vice operation is usually a fairly large undertaking. There won't be just one cop. It won't be just one day. It could weeks or even months of evidence gathering. These types of operations are risky, expensive, and can deliver very poor return on effort (# of convictions). So if you DO spot a cop, there are probably plenty more around you didn't see.

They will use every trick they can think of to make the operation successful. In one case in California, a private investigator was used (NOT a cop) who not only solicited, but actually paid for and had sex with a girl in the club. No cop would do that, right? Well, right, but she still got busted. So don't think you've got the "trick" to ratting out the cops and their agents.

Because of the above obstacles, true raids are not an everyday occurrence. People forget the danger. What it comes down to is this: be prepared to take the consequences of your actions.