For me, how a girl looks is almost irrelevant. Physical attraction is so subjective and your appearance is something that can't be changed...makeup and clothing only do so much. Besides, I have already made my decision whether or not there is a physical attraction based on pictures seen before. Granted, everyone loves a pretty face and that's not always shown, but that has rarely been an issue.
It's all about chemistry and me getting the feeling that this person wants to be there and enjoys what she does. The chemistry may not always be there, but I am usually very relaxed and easy going and I think that most people can get along with each other if there is a mutual attempt to be courteous and afford respect to the other person.
So if there's one thing that makes the difference and can be a learned response, it's appearing happy to be there. No doubt it can be hard at times depending on your mood, but if that feeling isn't really there, pretending it is might lighten the mood for the client and sp. And it works both ways...
A hug and/or a kiss upon opening the door is usually a good way to warm things up immediately, but I personally never do this, even a lot of the times I repeat. It feels weird to me to initiate a hug with someone I've never met - it's too immediately intimate. Not a touchy-feely kinda guy. But if the girl initiates, it's a nice gesture and a pleasant start.
Generally speaking though, if a girl seems disinterested and not trying, it's a huge turn-off. You're not going to get along with everybody, but I've noticed that the best and most popular girls have a reputation of making whoever they are with comfortable that they're always trying their best. Consummate professionals...