actually, my friend,

people are CERTAINLY judged by their appearance.

the hospital at which i did rotation in USA had a very strict dress code and i think its true for most of the proffesional companies, these dress codes are there for a reason. you cant dress like a hippy hip hop guy and appear at proffesional bodies.

proper dressing for the occasion is more than required. [unless of course, you are lady gaga.]

The appearance of someone can help us to know not what the person really is, but what the person wants us to see in her. For exemple, fashion choices can tell us about what the person want us to see in him. A person who is dress in a elegant way probably want you to think that he is elegant, polite and respectable, but also that those personnality traits are valued by him as a person. 

Of course judging someone on his appearance is natural, we cannot ignore the first impression we have about someone. And it can gives us clues to understand a person, know where the person is from, ect... That is the reason why it is important to what out for those details when you are in an intercultural context. 

If the first impression you have about someone can help you understand a person by giving you some information about her, you have to remember the interpretation your doing of those information is strictly subjective and can lead you to misunderstanding who the person is. 

To sum up what I just said, it is not unwise and even natural to judge a person about is apearance, but you have to keep in mind this jugement is superficial and there are other things you don't know about this person and among those things there is even some that goes against the first jugement you made. Trying to go further a first impression will help you open your mind and stop making the same mistakes.

I have to disagree on it that it is unwise to judge a person by its appearance.In fact,appearance says a lot what is inside especially when you look into it.This might be cruel,but it is quite true....

It is wise to judge people by thier appearance, it is unwise to express your judgement.

You don't know a person until you have dealt with him, until then appearance will have to do.

On the contrary. We have the ability to make judgments based on previous encounters. People like to say that they don't do it but they do all the time and for good reason. When approaching someone in the city to ask directions, you can be sure that these do gooders will be excluding creepy looking dudes for sure. This is a self preservation mechanism.