people are like that... some will allow your dick in there mouth, even your sperm, but won't kiss you.. So well... what can we say... Ask her to put a condom on your finger... maybe she will be ok with it LOL
There are a couple I know who do not allow digits and one of them told me it was because a lot of men do not trim their finger nails and scratch them which causes immense pain.
The big reason why I don't do this or have much talent for it is the fear of hurting the lady. Few escorts want digits, but some do. I have never been comfortable with it, so the latter have been disappointed. But, once there was an encounter where I used my fingers. I was very cautious, but I continued because she seemed to respond deeply. Somehow she had quite an explosive orgasm. Despite that one successful event I still worry about hurting a lady and won't try it any more.
My current favourite allows DATY, DFK, but no digits. I think it is her perogative. She's probably had clients handling cash which isn't the cleanest thing.
i think that most sps that don't allow fingers is because they were either cut or they got some infection/bacteria from unclean hands. even a micro-cut will hurt.
i've seen an sp that had a contraceptive sponge in her vagina. she told me about it. she allowed me to use my fingers.