What Would Make A Dogs Hair Fall Out And Skin Scaly?

There could be one of the following three reason behind the hair loss in dogs.
1. Allergy
2. Nutrient deficiency
3. Magne (Disease causing Hair fall and itchy skin)
I think yours is having the third problem, Magne. Magne is also of two types,
1. Pododermatitis magne (only affecting paws)
2. Demodectic mange, which harms the whole skin, resulting in patchy fur or scaly skin.
This is a contagious disease, even humans can get affected by it, so keep a little distance and take your dog to a vet. The dog suffering from this disease needs vaccination and proper medication.

I'm not a vet but from my own experiences with my previous dogs. Allergy in their food is the usual cause of hair fall and scaly alligator cracks in the dog's skin. ^^

Might have caught Mange. It can be treated by a vet.

Does his hair just fall out and then he is bald? Or is there just clumps of hair and hair underneath yet? I know both my dogs are shedding like mad but they are just losing clumps of there summer coat. It's normal for a dog to loose it's summer coat and get in a winter coat. But if your lab is just loosing hair and going bald I would probably take them to a vet and have them checked for cancer or anything else that can make them lose their hair.

Cut its hair and stick some scales

There can be any number of things that cause this. Poor diet, mange, low thyroid, allergies, fungal or bacterial infection, or any number of diseases including kidney disease.

If your dog smells like corn chips it is most likely a fungal infection. You can get anti-fungal shampoos. If it is something that happens every year at a certain time it can be seasonal alopecia, and there really isn't much you can do for that. Or it could be allergey related. If it is allergies an antihistamine can help. Diphenhydramine, the main ingredient in Benadry in the US, can be given. Talk to your vet about dosage.

It is best just to take you dog to the vet and had them run do a skin scraping and a complete blood panel. The skin scraping can tell if it is mange or an infection. The blood panel can check for diseases or low thyroid.

There are also hormonal diseases which can do this, which need specialised treatment from the vet.