Reports of Chinese illegals/failed asylum seekers/overstayers being caught are relatively few - either they're extra crafty or there's not that many.
95% of the germs reported seem to be from the Indian sub continent. If people stopped using "Indian" (aka Stani & Bangladeshi) Restaurants they'd be overcrowding Heathrow attempting to get home. The councils would also be able to save money by employing less Food Hygiene Inspectors