Sounds like your kitty is well cared for! These black flecks may not be flea dirt. Lets do a test. Take some of these black flecks in your hand and drip some water on them. With your finger rub them around in the water. If they turn red, they are flea dirt and it will be necessary to adjust your flea medication. Frontline is very safe, and you can apply it as often as every 2 weeks if needed. If that makes you nervous, or you don't want the expense of applying that often, you may want to switch to another flea preventative, such as feline advantage or revolution. Also be sure that you are applying the product correctly (you probably are but just in case). Part the hair down to the skin on the back of the kitty's head (not too low or on the nape of the neck because kitty can lick it off) and apply the entire contents of the tube to the skin. It is best to apply product before going to work or bed so you don't pat it off. Avoid bathing for at least 3 days after application. If you want to bathe the kitty before applying medication, wait until she is completely dry before application.
Your cat is 8 and is now considered geriatric :(. There are some illnesses that can effect major systems and that also includes her skin. Hyperthyroidism, Diabetes, and Kidney disease are the three major illnesses that afflict older kitties. These conditions can cause sufficient changes to bring about skin conditions. A comprehensive blood and thyroid panel can help diagnose the above mentioned illnesses. Your vet can advise you on how to manage what is going on.
Ringworm is a fungal infection which can lead to hair loss and skin changes. This fungus is contagious to you and to other pets so an exam and fungal culture may also be in order.
Be sure that the shampoo you are using is for cats and not for people. The Ph levels in our skin is very different from the levels of cats skin and using the wrong shampoo could make her skin worse.
Cats can also have allergies. Allergies usually show up as skin issues insteat of runny eyes and sneezing. Your vet can evaluate your pet and advise you on a proper course of action if allergies are suspected. Most of the treatment involves changing the diet to a novel protein source (think rabbit, duck, venison). These diets are prescription only.
Best of luck to you and your kitty. Please let me know if I can be of further assistance.