Most businesses have a note or sign to the effect "If you had a good time, tell others. If you did not, tell us." There is nothing wrong with asking a departing guest who says he or she enjoyed their stay to post on TA. If the guest did not have a good time, it would make matters worse to ask them to post, much less give a good review. I suspect that sometimes the staff does not get the message straight from management and just tells everyone to post a good review.