Any parallels? Are you required to pay just to gauge the appropriateness of an appointment with a doctor or lawyer? Or plumber? Or massage therapist? Realtor?

The application fee seems exploitive to me, something that exists because you can get away with it. I fully understand that many prospective 'clients' are only looking for the excitement of explaining their kinks, and are unproductive time wasters from the Mistress's perspective. But that happens in other personal services also. Not every inquiry results in revenue.

If a provider is concerned about wasted time, perhaps just limit inquiries to email. Scan the email and if it shows any potential, reply. If that doesn't seem to move things along towards possible revenue, then just move on.

But if I have a specific kink that I want to explore I'm not going to pay just to be able to ask the provider if she is comfortable with that kink, in a 45 second email exchange.