Responded to a BP ad via email, and she replied with a phone number, which corresponded to one review here.  It was a mediocre review and clearly not what I was looking for, so I declined without sharing any details other than, I saw a review and changed my mind.  She has subsequently asked where the review is located.  Should I tell her?

Sure why not? A lot of girls change the quality of what they provide once they realize it is being documented for others to see.

This is a public board.  She should be aware, on the off chance it is a fake review.

Good idea. Helps ensure both accuracy and the opportunity for improvement.