They're definitely in the clubs. Let me take everyone on a tour of Texas, where undercovers sit in bars full of college students and arrest/write tickets for public intoxication. No breathalyzer required for you to go to jail. All the officer has to do is smell alcohol on your breath, or see you take a sip. And good luck getting it dismissed, no matter who your lawyer is, unless you take it to the state supreme court.
Sounds like bullshit, huh, like I'm making this up.
Anyways, didn't mean to get on a soapbox. I spotted one of these guys, and I only knew he was an undercover because of the way he looked at me. I was at a bar rolling, walking around, smiling, having a godamn blast, flirting with girls, and I suddenly look over at a corner beside the bar. There's a big guy in his thirties just posted up next to the bar standing against the wall with his hands behind his back with a buzz cut and not talking to anyone. He keeps looking at me, and I'm just smiling and having a blast. Then, he ever so subtley shakes his head while maintaining a lock on my eyes, like, "you're fucked up and I want to see you in a cell." He didn't do anything, because I toned myself down when I realized he was one of these assholes.