These landlords (in most cases slumlords) have been using illegal aliens as cashcows for years. The can charge the illegals all the market will bear and they never have to worry about the illegal's complaining about problems with the apartments because of their fear of being reported to INS.
Landlords and business's that cater toward illegals and hire illegals should all be targeted with huge civil and criminal penalties. Many of the illegals will quickly go home or not come in the first place if they can't find a place to live, get a job, or even get a check cashed.
In fact, I'm of the opinion that you should have to provide proof that you are a citizen or in the country legally to get any utilities turned on, make any sort of wire transfers or other financial transactions or even make any large scale purchases such as a automobile or home.
They are slumlords, and they don't maintain their places.