How does your friend know that most don't speak English ? Has this friend spoken to every one of them, before telling you this story ?
Perhaps our own out-of-work people prefer to stay on the dole, rather then work ?
Perhaps these same people don't have the necessary skills that are required for the work ?
Too many unanswered questions here to form an opinion.
If you had used Polish people emmie, would they not have been good workers, who were clean, tidy, and not too costly as well, or are these qualities only available to British workers ?