Like other professionals, Sex Workers specialise and prefer to work in certain areas. For example one mechanic may only do engine work and yet another may only do panel beating.
Sex Workers also have specific skills and it is better to have someone see you who is comfortable and knowledgable about your needs and desires than someone who is not. If the first worker you call is not able to see you, do not be put off, as there are many other workers you can call. There might be lots of reasons why sex workers are unable to see any given client.