Can I tell a masseuse that her fingers smell horrible?
Why do you want to say it?
Because I want to make sure her hands are clean
I think that you were just trying to make sure that she was using proper hygiene. I think that there are better ways to go about it though. You should be kind about the words that you use.
Oh. I thought the reason people go to a masseuse is to feel good.
It is made to feel good, but you don't want to create more tension. You could politely bring up the issue to someone else instead. Make sure you are kind with how you say things to people around you.