Go to the CMMS website & research Conditions of Coverage for Nursing Homes. You can read through the regulations and find your answer if the nursing home has a Medicaid/Medicare provider number. The regulations can be vague and interpreted differently but this will give you a start. Good luck!
You can call your state office of aging. There are rules that apply to skilled nursing homes and the medicaid aspect doesn't change the law. BUT if your concern is that your loved one is getting bathed, it might be that the elder is refusing and most of the time they cannot force the person to be bathed. In that case you might talk with the director of nursing about options and your concerns.
The regulations can be vague and interpreted differently but this will give you a start.
Good luck!