TripAdvisor can be very useful if used properly. My main criticism with it is that it turns a lot of the people who use it into very spiteful overly critical amateur Hotel Inspectors, who are allowed to publish their reviews anonymously.
If you want to publish something vile and untrue about somewhere you've stayed, you should be made to put your contact details with that review. We had one on TA from someone who claimed they had an unsatisfactory experience, whilst staying with us in mid October 2010. Trouble was they didn't publish it on TA until May 2011.
Unfortunately for them we closed at the end of September that year as I had to go into Hospital for an op on the 2nd October and when I came out wasn't able to work again for 6 weeks.
That false review stayed on our site for the next 10 weeks until TA acknowledged it was a fake review but did nothing to revoke the 15 place drop in position we suffered as a result.