When I was growing up all you had to do was to yell "Immigracion" in a restaurant and the place would clear out. Now if you yell "immigacion," an illegal alien host will calmly walk up to you and ask you in Spanish where you want to sit.
I worked in LA manufacturing district in the early 80's and it was still the same then. All they had to do was see the green immigration vehicles and you would have a ghost town.