I think there's merit to your post, but I substituded 'cop' for 'black guy' and your sounds bigoted to me. It may be important to generalize and stereotype, but take care to recognize it.
Paragraph with the substitutions:
People believe black guys are bad because black guys do so many bad things. They have not taken responsibility as a group and purged their ranks of bad black guys, so people will continue to assume that every black guy is a bad black guy. This is the only rational assumption to make, because many of them are bad people, and they have power over you. Thus, you must be on your guard against bad black guys, and you must assume that any black guy interaction will go wrong.