I feel bad for homeless people too, but i generally don't let too many live in my house (at least not lately).
Ummm... why does everyone keep comparing the U.S. to their house? Your house is a piece of property where you and whoever you select live together. A country is... oh wait, I'm not a fourth grade social studies teacher. We all know what a country is, right? And this country is a "democracy." Which makes is different from your house. Also differently than your house, who is let into the nation is not regulated by who you do and don't "feel bad" for. Luckily.
Additionally, why do people keep comparing homeless people to immigrants? "The bottom of the barrel?" How about the people who were brave and bold enough to cross an extremely inhospitable border, move to a new country with a new culture, language, and system, and find a job. Have you ever moved to a new CITY? Its rough, man. I wouldn't say that those peope are the 'bottom of the barrel'.
Of course, I wouldn't say that about any of my fellow human beings.
I also believe that you will find many individuals of great intelectual worth who come here legally and illegally. Some refer to it as "the brain drain."
RE: How can Illegal Immigration help our Homeless situation?