The breed is the search. Owners of coated breeds know their dog needs a specialist and type the breed name, and a salon that names the breeds it works with regularly is found by exactly those people.
Coat problems are searched in a hurry. Matting, shedding and a dog that has not been groomed since last summer bring work that pays properly and that many salons quietly avoid.
Nervous and elderly dogs are a genuine niche. Owners search specifically for somebody patient, they travel further than any other client, and they stay for the rest of the dog's life.
The puppy's first groom is a small search with a long tail. It happens once, it is cheap, and it decides where that dog is groomed for the following twelve years.