If cops would wear uniforms and drive marked vehicles when doing cop work, there would be no need for more information, and grandpa would probably still be alive.
You are claiming that all undercover law enforcement operations are illegitimate. This is an utterly retarded assertion. If you consider yourself to be something other than a complete moron then please take a moment and ask yourself whether our nation should endure the effects of all of the organized crime and terrorism that are presently thwarted by the types of undercover law enforcement operations that have been a part of our society for generations. I don't care how stupid you are, if you think carefully you will change your mind.