Police in the US don't have to tell you what they're doing up until the point they decide to exercise their power (i.e. searches or arrests) either, last time I checked. They can ask you to go somewhere and you can voluntarily comply or choose not to.
So you are OK with women police officers dressing up as prostitutes to attract potential costumers and then arresting them on the spot ? That's extremely twisted. There's a reason why in many countries police officers HAVE to wear uniforms.
Yes? I'm pretty okay with this. I'm okay with police going undercover, too, to bust up gangs. It turns out that policework is more than just standing in a pretty uniform.