Sometimes an escort will opt out of reviews because they have had an arsehole client who has threatened a bad review on them and the girl might not be well known enough to get it taken down by the mods here.
Usually though it means that they are not like the photos or offer a crap service and their run of easily pleased punters has run out.
You could always post a thread and ask people to pm you their opinions but don't do that if you can't handle the truth.