Chicken-processing plants attract a lot of illegals but housekeepers are mostly illegals and they are everywhere. I know that illegals have been bused into Chicago by the thousands, they are in Long Island, they are just about everywhere. Every state is a border state now. But I believe that many of these nice places like good hotels, restaurants, upscale stores and hotels are being cleaned by illegal alien crews.
Undoubtedly both guests and housekeepers are involved in the spread, but of course the guests are bringing in luggage, whereas the workers typically bring no personal possessions into the room other than their own clothes.