If some of this was covered in previous posts on this thread, I apologize. I did not read all of them.
To Esmith.
National City’s hispanic component is generally regarded as Chicano (as I technically am) and not Mexican. In other words, people whose grandparents and great-grandparents came over the border. Alternatively, some saw the border change and so therefore the country they lived in. Those areas generally do not have a high percentage of illegals. It is always hard to tell when you have a group that is averse to being identified so numbers are always slippery but this is why Oceanside probably has more illegals than East Los Angeles.
As a professional, I have seen only a few buyers that appeared to be using a relatives papers for purchasing. Even then it was structured as the legal resident purchasing and showing up to fill out forms. Usually, they referred to the relative without papers as their “advisor” or “assistant” so the real arrangement was unclear. I speak Spanish (which my clients don’t realize) and there was never open discussion about it. My point here is that I doubt there were huge effects on itinerant illegals but maybe someone else has better information?