Do you live with/care for your father? If so, then after he goes to bed, take his clothes from his room and either replace them with fresh, or wash them and then put them back in his room. I had the same problem with my mother and this is what I had to do. Before Alzheimer's she was NEVER like this. She would shower daily and put on fresh clothes. Now, showers are a real struggle. Since the disease has progressed, she is not aware how often she is changing clothes; her short term memory is pretty much gone, so that is no longer an issue.
I wish you well in your journey with your dad.