I'm in the habit now of asking what the gentleman prefers if he doesn't say in the initial contact. (Guys, another great reason why booking the day before is beneficial to you, we have time to shop and provide exactly what you want to see when we open the door.)
Being undressed is just as arousing for me as it is for you. It's the same affect as the double takes and lingering stares when out and dressed up for the night but so much more intense when in an intimate setting. Unfortunately, some don't treat the presentation as a gift box but more of a "It's Christmas Day 1991 and that better be a Super Nintendo under that wrapping!"
So yeah, always speak up on what you want. I'm still going to go in sexy, but it helps to know if I should sport a crotchless number instead.