Examining something are culture doesn't.

I want to talk about judging people by just looking at them, and this might seem like I'm going to stand on a soap box and pull out a race card when really i just want to explore something that culturally we think and/or know is bad, but yet don't really talk about it, unless it's in contrived ways with after school specials on TV. Not sure if i have anything meaningful to really say other than "Why don't we talk about this?"

Let me start with a experience i once had for a example of what i'm talking about.
My next door neighbor and I were and still are good friends; anyways he has this friend that basically looks Irish with a red beard and is about 25 to 30's. at the time we both were in are mid teens so i'm guessing i was 16 max, so my friends must have been 15. Now i have no problem with hanging out with people not in your age bracket, since I have one a good friend that I met at college who is at least 30 if not 35; I use to hang out, a lot, with my neighbors little brother who is awesome and about 10 years younger than me. Anyways i see my friend's, friend and i take a instant dislike to the guy. The thought that passed though my mind are that he's immature yet he had said nothing, and really hadn't done anything. I'm fairly sure he also took a dislike to me at that same moment or maybe afterwards. Could be my mind playing tricks on me.

We have never had a conversation, but I still have a dislike for him. Originally i wouldn't be shocked if i felt threaten and had been possessive but now, it seems like more like a dislike like of this persons life style or i guess this assumed maturity level i see him at. I'll give examples that i am fully aware don't show him in a good light, and in fact make me look horrible for having these problems but they are all i have to compare him with. Don't look at these as confirmations that i am correct, but look at these as my point of view.

Once i was walking by his house and he barked at me to get away from his truck. From what i can tell, he parks it on the curb, and a bit on the road in fact.(He's totally EVIL!!!)
Near his house on the road, there is a crude chalk drawing of a penis that I assumed he or his friends drew. (flimsy, silly, and makes me look like a jerk for the assumption i know.)
While walking by his house one time, one of his friends tried to sneak up on me, and fire a airsoft pistol at me from i guess four feet away. He wasn't that stealthy.

Looking at these reasons I've written down, i sound like a crazy person who wants to hate this person just to hate him. I do think that for this instants there might be something else going on. I believe that some type of instinct decided that his person mentally or socially is unhealthy for me, and/or the people around me; so i've decided to protect myself by hating/disliking him. In a way this is also protecting my friend in a moderate way, because if we don't all hang out together, than it lowers his interaction with the person.

Now, is this person who I have had no real conversation with, bad, immature, or dangerous? I don't really know, beyond what my feeling tell me. I wouldn't say he's dangerous but immature, and bad, i guess so. Is this a reason to dislike him without talking with him? Well from everything I've learned from media, of course it's bad because the mother character says so; however is it really bad? take a electric stove, turn a burner to high, and the black coil turns red; it wouldn't be intelligent to place your hand on that burner. Now look at a black metal door knob and it starts to turn red, do i really need to touch it with my hand to figure out if this is painful to touch? Well yes, you do but it's not like i'm going to suggest you do such a thing.