are all about bait and switch.  Its intuitive of you to think that SOME of the photos are real, but its mostly the ones of the ugly girls.  Its a minefield.  Careful where you step.  

Technology is your friend here...  

 
Try doing a reverse image search on these pics.  

 
You will find them across multiple sites - AS, rub ratings, sumosearch (never heard of this one before...)  
In multiple cities - LA, Anaheim, Atlanta, New York, Chicago
And with multiple names - Faith, Valeria, Melanie

 
Try to google search the phone number type in "999-999-9999" format.

No useful hits at all, like other escort ads consistent with this one, or an agency ad that has multiple models available to book under that number.    

 
Fake ad.  

 
Life is good

 
The Cat

In some areas, AS can be a good platform for legitimate providers. Even some ads with higher quality pictures are legit. But you have got to do your research. Many of the ads exist just to collect phone numbers and email addresses to sell as marketing lists.