Some girls post rates in their ads and some do not. Curiuos to know if there is a bust, can those rates in the ads be used as evidence in court as intent to perform or pay for alleged sexual service for the provider and the customer. Even if the actual ad does not get specific about things done in a session.  Some will just say $300 for one hr, $175 for 1/2 hr.

First and foremost, the gals will state that the rates are not for sex, but for escorting, which is legal.

Next, for the website to be entered into evidence, all kinds of technical issues over who controls the site, etc. have to be met; and that can be expensive and time consumming for what is, after all, just a misdeamenor in most cases.  In some high profile cases however, mostly for large agency busts, websites have been presented as evidence.

(still not a lawyer)

Anything within the ad can potentially be used as evidence even if the ad says compensation is for time only....etc...

The classic rule of law is that advertising is just puffing and not to be taken very seriously. Generally speaking it will not be entered into evidence unless through a legal loop hole. Intent to perform, as you put it, is a creative concept but not too worry, it takes more than that to get you snagged. In practice listing prices may save you time and avoid having to talk about them which can lead to trouble and become evidence of solicitation. Since TER lists rates, you might avoid any prices if you feel you can rely on the the members of TER, I never thought listing prices was a classy thing to do but I understand why they are listed. Some famous providers do not list prices and prefer to deal with this on a face to face basis.