@Margret32 Can they do what? Leave a review? Of course they can. But don't get all anxious about them leaving a bad review- if they told you your place was wonderful, they may very well leave a nice review. Sometimes people's plans change, but they don't always necessarily make that the host's problem, and don't expect a refund. Sometimes hosts are blindsided by a bad review from a guest who was nothing but nice and had no complaints during the stay, other times the host anticipates a bad review, only to get a glowing one.
You could hold off on reviewing them until you see if they leave a review or not, but if they do leave one, just leave an honest one for them. Did they leave it clean? Did they follow the rules? You can never go wrong being honest.