There was an article hitting on this topic a few days back in the LA Times:
http://www.l
atimes.com/news/printedition/la-me-dream26jun26,1,3779486.story

Not all illegal immigrants are poor. There are many wealthy ones who come here from Taiwan, for example. Just look at Irvine, California, where home prices are high and probably won’t go down much. Half of China seems to be living in Irvine! Wealthy illegals can keep the housing market up in some areas, I believe.