Let's see... as a white guy who grew up in a small town, I should have a few, right? I'm going to list out every one I can think of:
-Be 15, playing with bouncy balls with some friends in an empty public parking lot behind a shopping mall. Cop shows up, makes us all show ID, tells us to go home. Lame.
-Be 15 again, spend a weekend building a potato cannon with my friends (remarkable feat of engineering, I'll add), go out to a public park to test it out. No other people in sight, we're well clear of any buildings or property, not endangering anyone (except maybe ourselves). Cop drives by, stops, tell us we're in possession of an unlicensed firearm, calls my parents and sends us home. LAME.
-Be 16, dressed in costumes, filming a silly movie for a school project outside another shopping mall. Cops show up, ask us what we're doing, say we can't film there (we had permission), calls our parents and sends us home. Lame.
-Be 18, driving my younger (16 year old) sister and her (16 year old) friend home from a party. Obeying the speed limit and all traffic laws. Cop pulls me over, makes everyone show ID, asks sister's friend if I'm abducting her or if she's there voluntarily. She's there voluntarily. Sends us on our way. Lame.
-Be 18, getting busy with my girlfriend (17) in a parked car. There's a bright light in the window, followed by a tap. Cop motions to us from outside the window. Pervert stares at my naked girlfriend and myself as I struggle to put on pants and go outside. Cop: "What are you guys doing in there?" Me: "Uh... relaxing?" (seriously?) Cop: "I need some ID". Checks our IDs, basically tells us he thinks I'm raping her, despite our explanation to the contrary. Makes us stand outside (she is wearing only a blanket) while he searches the car. Finally lets us go. Lame.
-Be 27, living in another city. Call the cops for a noise complaint on our upstairs neighbor, who is screaming at us and banging on our door and stomping around at 3am on a Wednesday. We're worried for our safety. Cops never show up, I spend the rest of the night clutching a baseball bat. I later get a call telling me the cops came by at 6am (long after everyone's gone back to sleep), didn't hear anything (never even came in the building), and that I should refrain from making false complaints in the future. LAME.
-Be 28, stuck at a traffic intersection for 5 cycles of the traffic light. A cop car is blocking one of the lanes (harassing some homeless guy), throwing off the traffic pattern, causing gridlock. Someone needs to direct traffic to make one lane stop turning periodically so the other lanes can clear. I get out to ask the cops if they can help. They tell me to fuck off (actually said "fuck off") and to get back in my vehicle. Some other citizen hero eventually steps up and directs traffic to fix the issue. Lame.
tl;dr - I'm a white guy, never got shot by the police, so yes I'd say every one of my experiences has been positive.