For the record, I hate that word. It, like the "n" word, says much more about the person who uses it than its intended subject.
Just for the record.
The "n-word" indeed does what you said, but "wetback" is descriptive and specific.
N-word is a vile racial slur unfairly applied by bigoted morons (including rappers) to all black people. Skin color is meaningless, benign, and certainly not the doing of the targeted individual.
Just for the record...
"Wetback" details the immediate condition upon arriving in US territory as an illegal alien having crossed or swam the Rio Grand...(wet)...which is absolutely a decision and action taken by the criminal trespasser, who should be apprehended, prosecuted and deported.
I don't have any problem referring to them with a descriptive term. By the way, there are also "drybacks". Is that offensive to you too?
"Wetback" does not apply to the invader's relatives who stayed home, nor to any of his relatives on this side of the border, who have acquired residency in a legal fashion, either with a work visa, or who has gained US citizenship.
I'm not even sure it applies to any particular color of skin pigmentaion..
Just for the record; the word "race" is racist.