Personally, I'd say it's not much of a poll because it doesn't actually show one's opinion on the issue. I don't think illegal immigrants are a blight on our society, and it makes little difference to me that they are breaking the law every second they are here -- but how can I vote that illegal immigrants are not illegal immigrants? They are, by definition. Rather than couching it in terms of a definition, it should have asked the original poster's real question: are they a blight on society, or are they a benefit to our economy, etc.?
I'd vote that illegal immigrants are like any other demographic group you could name: they break laws, they uphold laws; some work, some don't work, some commit crimes. Some are a burden, some are a boon. The only difference between illegal immigrants and other people here is that, because of their status, they are easier to single out and use as scapegoats.