I agree that we all are human, illegal status or not, and I always strive daily to treat each person I meet with respect. But female illegals who con American guys ("undocumented" gorgeous seductive Latinas are not the only ones who dupe their future husbands...I heard of an illegal Asian lady who did the same... about 2 days after she obtained her green card, she filed for divorce; the poor schlub ex-husband was left an emotional wreck) into marriage are considering, the very least, something quite unethical. I'm unmarried, but I think I would be highly ticked off if I found out my fiancee was using me to be rid of her illegal status, and not because I'm her real life partner. Believe me, I'd file divorce papers immediately, and hopefully for her, I don't give the local INS office a ring.
I don't really think you can blame it on the people that fall for them. If somebody marries another for a reason other than out of pure love, than they're not very nice. The person who marries them, must love them if they accept them as their life partner by marrying them.