I am the complete opposite from you. Deposits are an inconvenience I can put up with. But for the mistresses I have a connection with, and probably Mistress Ayn would be one if we got to know each other, I would feel offended. I would still pay, but I would trust less somebody who knows me but still does not trust me. Fortunately this has not happened yet, and I do not speak only about mistresses.

On a side note, you should understand that a mistress has a lot of overhead so not showing up for a meeting without ample notice means stiffing her and more often than not even financial loss if she had to reserve the dungeon. Compensating for that is a matter of correctness and should have nothing to do with how much you like her.