The debate over immigration is heating up. People, mostly on the restrictive side, often refer to "low-skilled or unskilled immigrants". We need to be careful of context--there's two societies involved: the U.S. and the country of origin; so comparisons and social ladders in one society don't match up with those in another.
My impression is that the vast majority of immigrants of working age have to come up with a fair amount of money in their native country in order to get into the U.S. Indeed, illegal immigrants probably have to pay more than legal immigrants. (A "coyote" on the Mexican border costs more than an airline ticket from whereever.) That assumed fact leads me to believe that the future immigrants, while in their country of origin, had skills. They weren't the "lowest of the low" there. They may be doing jobs "Americans won't do" here, but that reflects the differences in the two societies and is not a basis for looking down on them. [ed.--do I heard a comment that of course we don't look down on people? Remember the Bible's beam and mote in the eye.]