When I first saw that ad, the first thing that came to my mind was… probably BS

From what I have heard is that some of guys from the Seattle area say it is bait and switch. In fact this particular so called agency is never talked about much on the independent local Seattle board

There is something called the Puget Sound escorts network, where they keep track of clients personal info…ok just the bad clients personal info…HAHA.  I’m not positive if this network is connected to the agency?

Here is a post about this particular agency

I think if you just want something right now with no hassles, you can take your chances with the yellow pages or these types of services, and in most cases you'll be ok. If you want to get references checked(wait time), and maybe pay a little more; then stick with reviews on this site or others like it that have a good rep.
I hear that these services are not cheap by any means because the rate is up to the lady and rates are not set, if you get my drift. Getting ripped off or bait and switched are only two low level concerns when doing 'this'. There are a lot of other concerns that are more important and will not matter to you until you are facing 'it'.
PS. I know that the pics are just representative of the types of ladies they have available. I know because I wanted to use my own, back when I first started, and it was a no go. They can't keep changing the pics every time someone leaves. Maybe if a gal stays long enough she is represented..but it's rare.