Seborrhea and no self grooming

My new foster cat from the local shelter has ugly greasy fur and dandruff. I might be some medical condition that causes it, but I wonder if this happens because she does not groom herself. She is also a little smelly. I am thinking of giving her a bath. Any suggestions for a good shampoo that will help her greasy fur? Or idea how to make her groom herself? Diet suggestions? Right now I feed her "Merrick´s Senior". Shelter staff estimated her about 8 years old, but her body looks much older to me - bony and stiff in her movements.

I hope to get her looking and feeling better and find a permanent home.

I'll move your post to the Care & Grooming forum, where I think you'll get more replies. Making the most of it still being in health, I will say that nutrition can definitely affect the coat. She may also have additional issues, possibly arthritis (since you mentioned stiffness in movements) preventing her from grooming properly.

Has she been seen by a vet at the shelter? I would definitely bring this up on her next check-up, as well as skin parasites and possible allergies.

Moving your thread to the grooming forum where I hope you can get some recommendations for cat shampoos. Until then, here's a link to our Cat Shampoos Reviews section.