What does illegal look like Arizona?

So today Arizona's governor signed a bill that would give police the "freedom" to check and see if someone is an illegal immigrant. What does an illegal immigrant look like? Mexican, Nigerian, greasy, short, tall? Do they cut grass, or drive taxi's? How would you know? I have a feeling that this bill will cause a whole lot of problems. It seems like 1984 to me. Hopefully the thought police don't get more for writing this brief blog.