First Impressions and generalizations…be careful about them.
Not because one poor person you know is lazy makes all poor persons lazy. Similarly, not because one wealthy person you know is corrupt makes all wealthy persons corrupt. The same goes for first impressions. Don’t judge persons on the clothes they wear, the way they (don’t) comb their hair or the street they live on.
Making decisions based on these perceptions may cost you significantly in the long run.
I have developed my own system of always giving persons a certain amount of respect. Let say 50% in order to quantify it. It is then up to that persons to loose or further gain my respect. I have noticed that always treating persons with respect usually brings out the best in them.
Encourage open mindedness!