Listen I know this is a horrid thought and you have all probably agonised long and hard before putting your loved one into care but I just wanted you to know what I know from my many many visits to care homes (and phone calls I have made when not happy with what I have seen).
Even when your care home choice is seen to be one of the best it only takes one evil carer to make a person's life a misery. In one care home the children were totally unaware of the abuse until their mother screamed when one particular carer got near her. Eventually they checked their mum over for signs of abuse and nothing no marks, scratches or bruises until they looked under her arms which in people with severely restricted mobility is really hard to do. One carer while apparently 'helping' their mother to stand was in actual fact pinching the delicate underarm skin so hard she was bruised really badly from it. Of course their mother stood or tried to she was in agony from this evil witch who incidentally has been dealt with through the courts.
So please do conduct spot checks to make sure your Mum's care is everything you expect it to be.....and people wonder why a) I wont put my mum in care and b) I want to be able to choose when I die!