I doubt the say hey I am an undercover cop, lol. I agree it defeats the purpose. But hey Scotus said they gotta disclose them...so that is how they are done.
Ok. But it was the SCOM (Supreme Court of Mass.). Where I live (Calif.) it is apparently legal for the city to videotape citizens without asking first. They have cameras in the downtown area with recorders on them, and I have never been "officially" notified. My point is: "What is good for the goose, is good for the gander."