I think it's a reasonable request if they haven't already showered. But you're assuming they haven't showered. If I'm doing outcalls I Factor in a shower and I shower before I leave my home. If I have an appointment they're usually pretty good about letting me shower And if i'm far away from home and my last appointment didn't want me to shower there because they were pressed for time or I didn't feel comfortable or for whatever reason, I will Let my next appointment know that I need to have a shower before we get started. Most people are pretty respectful. I personally don't want to get started if I don't have a shower but you're assuming that she did not shower. When people go out of their way to put a lot of emphasis on a certain thing, sometimes you're implying a lot of really negative stigmatizing things.
The assumption there is, she's dirty and that she doesn't shower and she's not clean when she very well could have had a shower before she left her home. Most of the time her last call will let her shower afterwards. I don't even have to ask. Most people just offer to let me use the shower.
I know it's a very real concern for you. But sometimes people take their concerns to the next level and it comes off as offensive. They get tunnel vision and forget they're talking to a real person.
If the person has already showered and You request that they have a shower because it's really important to you I personally would Include it in the session. Because I'm specifically taking a shower to please you, where I wouldn't necessarily need one because i've already taken one. The shower is for you and you alone. It wouldn't be for me. It would be to put your mind at ease. If i've already showered and put my makeup on and done all of the things and put lotion on it's more of an Inconvenience for me to hop in that shower. Now my hair is wet, my makeup is sweaty. My lotion or whatever is washed off.
I'm not saying it's not a reasonable expectation for someone to shower... But if they have already showered and come prepared to the appointment, but its absolutely imperative, to you that they have a shower to prove to you that they have showered. I would absolutely make it part of the appointment. Because i'm not doing it for me at that point, I'm not doing it for cleanliness. I'm doing it to resolve your paranoia.