Well I guess one approach to test your anecdotal "evidence" is to make it very difficult to hire illegals, and see how high the wages rise. If "spic work" wages rise above 25 bucks an hour (that's 50K a year), I would be surprised. As I say, some of the work will become more mechanized over time. If the wages rise to 40 bucks an hour, then that would create a very good case to increase the number of legal immigrants.
The "spic wages" were $25/hr for a job made in heaven for a young, healthy, unskilled, unemployed, no H.S. member of the National Guard.