Stating the obvious, you could avoid disappointment by just seeing younger providers. Lord knows there are plenty of high quality choices in the early to mid 20s. How young do you want them to be?
I guess my question would be: in what way would it benefit you personally to point out in a review that a woman is older than she says she is on her website? What would be the fallout for you, personally? How would it benefit the hobby community? What would be the consequences for her?
To out someone for anything, you have to have proof. You can't just go by what you guess, because that is just conjecture and purely subjective, right? If you had 10 guys in a room with the same woman and told them all to guess her age, you wouldn't get 10 identical answers. You might skew older -- women might appear older to you, just from your frame of reference. Some people look older than their age, because they smoke, for example. I happen to look younger than my age. People are usually surprised when I tell them my age. So you'd have to see her driver's license to be sure. And I don't think that will happen. So why put yourself in that position? You wouldn't appear credible, either.
It would be one thing if someone flaked on you, didn't show, was less than enthusiastic, was not clean, etc., etc. Those might be something you might genuinely point out in a review, if you were so inclined to alert the community about a negative experience.
But if you weren't 100% positive about something that is opinion-related, that is really different. Someone being late is a hard fact. Someone appearing older than you expected is more of a guess. And your "guess" is impacting her livelihood. So, no, if I were a hobbyist I wouldn't go there.
If you saw someone who was rated a 9 repeatedly but she wasn't what you expected, you could always rate her less and then it seems like that would take care of the issue right there, without you jumping into the deep end of conjecture. After all, a rating is just one man's opinion.
I don't know how clients get blacklisted or if there even is a blacklist but they get bad reps for being violent, stiffing, and ncns. These occurrences are RARE. That's the only reasons why I have heard of anyone getting a bad rep, e.g. on date-check. I don't think you would get blacklisted for something you said in a review. People say stuff in reviews, I think we all know that. I think we all get that reviews are not gospel. It could be that there is something I don't know about but I kind of doubt it. Providers might be less likely to see you but that is not the same thing as being blacklisted, is it?