This issue hangs around because every professional married couple in the major metropolitan areas has a nanny, a housekeeper, a lawn boy, pool boy, clean-up crew, carpenter-on-call, etc., and they love to have all of these at half price. They are the ones who need to be brought out into the sunshine. I know for a fact (personally know) that at least one mid-level IRS official in the D.C. area pays her housekeeper cash and knows full well that this employee does not, CANNOT declare income.
Romney himself was busted for illegals, the same crew, twice.