Where can I look for a quote could I use from To Kill a Mockingbird to show how 'judging a person by their appearance will change people's perspective on who they truly are'?
Dolphus Raymond is the clearest example of a character that presents a deceiving front in public. The town of Maycomb watches Raymond come to town and drink from a bottle kept in a paper bag, assuming that the bottle is full of whiskey.
Not only does Raymond allow people to falsely believe that he is a drunkard - he encourages this view, adding flair to his public appearances by acting out the part (he weaves when he walks, etc.).
He fosters a reputation as a drunk to give townspeople a reason to excuse his flaunting of social taboos.
Upon meeting Raymond, Scout and Dill realize that he is not a bad person and not a drunkard at all. He simply wants to be allowed to be himself. In this effort, he tries to make things easy on the townspeople by maintaining the role of the drunkard.
When Scout sees Raymond for the first time, she is convinced like the rest of the town that he is really drinking whiskey and living a disreputable life. Her views of Raymond masked the reality of the man, skewing her perspective toward the shared fantasy of the town.
Scout encounters the lesson again in the guise of Mr. Raymond:
No matter what role people play in society, they are probably similar underneath.