Man, it's all in good fun. Just test the waters, you never know what you may like. I was personally ecstatic about the appearance and voice of a provider I saw who didn't show their face. I was expecting a big mama bear (and I was OK with that as I will fuck anything with a hole). Nevertheless, she was great and it made for a great session!
For me, even if the appearance isn't up to par with what I expect, I go through with it anyway. Most providers will show you a great time especially when you're cordial and clean. You never know, the "but-her face" maybe the best bj or fuck you've ever had. To me it's less about the black/white and mechanicals, it's more about having a new experience.