I gotta agree with Rolo on this one, MLC. If someone books a dinner date and lets the SP know where the restaurant is, she should take the time to know what is "normal" dress for the establishment and show up accordingly.
Now if she just happens to dress a bit sexier and more revealing than most women, that's a matter of personal opinion. The same black cocktail dress that looks "common" on one woman can be outrageously sensual and eye-catching on a woman who has the curves and struts with attitude.
And let's face it -- most of us are there not just for dinner, but so everyone else can see what a gorgeous lady is at our side. If all you really wanted was dinner and "dessert", you could have ordered room-service to the hotel or had something catered.
I am curious as to what Fernie defines as "trashy", given that the vast majority of SPs I've seen showed up in an outfit that would be just fine for a 3-4 star restaurant, and even a few 5's.