On more than one occasion I have had guests leave bad reviews on my property that are unwarranted (rather obvious from all of the excellent reviews). The most recent negative review was from a guest that complained that the lake level was lower than that which was shown in some of the site photos. The review didn't say a thing about the property itself but thought the level of a lake that is controlled by a government entity was somehow my problem.
VRBO does not allow a review to be removed unless there is written proof that extortion was involved according to their security people. Even after submitting proof of extortion they wouldn't remove a prior negative review. Their system is rigged to give the guests lots of options to damage the business of a host while not having any consequences for the guest.