Today in our terror-stricken American society, Muslims and all those of middle eastern origin are definitely demonized. Teenagers are also conceived as "impolite thieves". The media, the fear that all Americans have (which is spread through the media), and prejudice all contributes to these pre-conceived, ignorant notions.
Ever since the beginning of western civilization, most Americans have had a strong disliking for Middle Eastern people. A combination of factors causes this. The fact that they're culture and religion is so different has one thing to do with it - Americans can't stand anyone else doing anything but what they do; look at the "assimilation" era in which the government gave money to Native American children so that they'd go to school and be told that what they and their ancestors had been doing for centuries was wrong and unethical. Another reason is that the government and media refer to "terrorists" as no one but middle easterners.
This strikes fear in many Americans. What is the KKK? I've never heard them called terrorists, but aren't they?
The general American public thinks that if a man with a turban gets on a plane with them, they're a terrorist. A brown-skinned man driving a van over a bridge? Uh-oh. That fear, the underlying prickly, crawly, panic, is what makes this prejudice occur. And nearly every single time the fear is unwarranted.
Teenagers are also demonized. Enter a corner store - you get the cashier coming up to you, interrogating you with his eyes, asking "May I help you?" This translates to "buy something quickly or leave." Yes, teenagers have stolen things - but do they all? There is not much to say on this, except for the fact that it's a bad stereotype, and I wish it would...