This is a really great and thought provoking topic to discuss both for SP's and for clientele.
One of the best methods of problem solving is prevention. If clients were to make proposals offering SPs a cancelation compensation if they were like the photos but not exactly what expected, I bet the honest ones would come forward with confidence.It might be a bit awkward and off putting for some but not for considerate or cooperative people.
Making an agreement to a cancelation policy around $50 can ease a bit of tension when it comes to photo specifics; for example, if the SP looks the same or very similar to the images, but the client imagined a slightly different persona and does not want to see the SP because of it, then that would be a fair reason for a cancelation compensation; but if the girl looks nothing as described, then the client should leave or tell her to leave asap.
There are many fake photos out there used as bait, and on the contrary, many who do use real photos either don't look the same, or they don't show their faces leaving room for misconceptions. " I like what I see and since your photos only reveal so much, how about if we plan for you to come over for the hourZ? If you are not the girl in the photos, you will be asked to leave without compensation, and if I have a problem with what the photos don't reveal, then I will give you a $50 cancelation fee for your time?" Does that sound reasonable?
The SP could also offer a 15 min session. I do, and many actually will read my fabulous reviews,

chose to see me for the 15, but are usually sure to extend (if I can) and come back at a different date. I look different in my photos than I do in person and many people do. I try to show as much as possible in photos so that I am not turned down.
From my experience, there can be much dishonesty with third parties; so it is wise to select independents over agencies that are not well known.
There are agencies (or small organizations to watch out for) who hire girls and don't portray their real photos in advertisements; they post a look a like, the client calls a line, speaks to a booking girl who pretends to be the girl (in one of the 10 girls who are being advertised listed in a row as independent) who is going to see the guy. The Sp is sent out, meets the guy and he is upset, the SP is stressed out about the unhappy client, she takes the blame, collects the money, and the agency just benefits off misfortune. That has to be one of the most stressful things about this industry I faced as a beginning SP. It did not take me long after to become independent. I just question how many organizations are up and currently running that way, and if not why would any honest, independent worker want to lead themselves into misfortune by portraying an identity with fake photos? I am pretty sure the majority of Sp's don't want to cheat or to portray themselves as rip off's. I think the majority of SP's want to look good in their photos but realistic, and then there is less room for disappointments when there are first time meetings. Many SP's show very sexy and accurate body shots, not including the face, so the photos are real, but because they dont show or reveal everything, that could leave room for misconception and be a good enough reason to set a cancelation policy or offer a compensation just to take the edge off of disappointment, embarrassment and time invested. A type of agreement before hand or offering a cancelation allotment is a good question to pose as a test to detect real VS fakes, it is a fair "ahead of time" agreement that both client and SP can make as a type of insurance, and it's a fair agreement to make so time and money are not wasted.