This is some sort of instinct we have. I see plenty of people like this every day: ones I feel an instant and irrational dislike for, and ones that I feel sympathy for for equally irrational reasons. If I actually got to know them on a personal level my feelings might be the opposite. This is a luxury most of us don't have, and making shotgun decisions about strangers we see on a daily basis is natural.
Human Resources departments and interviewers have a first impression of people the moment they see them, which in all likelihood will determine whether that person gets the job or not in many cases. Would you rather hire a totally qualified person who you have a distinct irrational dislike for, or a less qualified person who you immediately feel comfortable and friendly towards? These feelings are in all of us. They are human feelings and there is really nothing that can override them. The only totally fair way to make hiring decisions would be to see resumes with no names on them (as many HR departments are either pro or anti man/woman). Instead of asking questions face to face candidates for a job should be given a questionnaire to fill out with whatever a normal interview would have had. It is only after this and after a decision has been made for the most qualified candidate would I consider an interview process to be totally fair.
There is no point in denying that many of our decisions are make for seemingly irrational reasons. This then begs the question how irrational are "irrational" feelings? They are part of our instincts, which have been honed over hundreds of thousands of years to keep us from danger.
All of us have seen strangers who we instantly dislike because they are: too fat; too skinny; too perfect; bald; have dyed hair; have bad teeth; have perfect teeth; seem arrogant; seem stupid; seem rich; seem dangerous; seem better off than we are; have a mustache; have a beard; have stubble; seem like they have had plastic surgery; seem lazy; look like yuppies; have an expensive car; have an old pick-up truck; have a hot girlfriend; have an ugly girlfriend etc etc.
And of course there are people who just have something about them that makes us instantly hate them. It seems inexplicable. We could feel bad about it, but then again we can just take it for what is is: our instincts talking to us. You'll probably never see that person again, so just go with it. Just remember, other people are constantly sizing you up on a daily basis too, and they either instantly like you, dislike you, or see right through you and you leave no mark on their feelings either way. That's just the way things are.
Even babies are known to prefer one total strangers face over another during experiments done with photos. It's not bad to embrace our instincts. You never know, maybe our seemingly irrational likes and dislikes aren't that irrational after all.