Nursing homes operate on the honor system - pretty much the same way that all medical care is provided.  They are able to put their own spin on anything, making it difficult to hold them accountable.  
     Take a recent family member's situation.  He was in his mid 50's, with one leg amputated and in need of 24-hour care.  When we walked into the room to visit him, the staff was rude as hell.  One nurse threw away the power of attorney (healthcare) form he had completed and the family had to scramble to get another one faxed to them when he was signed onto hospice.  The nursing home social worker then refused to honor the document and completed another one with him, naming a friend as his decision-maker - even though he wasn't able to make decisions at that point.  They treated the family like shit, gave him full meals even though he had no teeth and was dying.  We walked into the room to find this cold meal:

He had bedsores, he was in pain and the staff was apathetic, and when I pointed out he wasn't able to eat the meal (above) they told me that "dietary services decides who gets what."   I pointed out to them that not only was it obvious the food had been sitting there for some time and he wasn't able to chew it, the grizzle on the meat was disgusting and inedible.  They told me it wasn't their problem and pretended to take a phone call.  
     Another friend had a family member there and they said that their experience was worse - and that they hadn't had one positive encounter with the staff there.  This nursing home received a "Two star = below average" rating from Medicare.  Yet it receives the same reimbursement from Medicare and Medicaid and other than paying a few fines, are allowed to continue to provide shitty-ass care.  It's cheaper to pay the fines than it is to provide quality care from caring professionals.