vrbo and flip key - the vacation rental section of trip adviser - now only allow reviews from people who stayed in the house, so reviews should give an overall accurate picture with the odd obvious anomaly here or there.
As a home owner if I get a new review I get an email from each asking if xxx stayed in the house prior to them posting the review, but I don't get to see the review. If they did stay they post the review, if they didn't they investigate it further and won't post it if they didn't stay. it's a much better system for all concerned.
Previously - like a year or two back - anyone could submit a review, from your jealous neighbor/competition to your upset ex husband/wife. It was tough and I don't have an ex wife..........