If you read a lot of the hotel reviews on this site, the fake ones are easy to spot.
First time contributions by people who never logged on the site again is a hint, but there are many others.
Creepy, robotic "Stepford wives" tone, with short sentences and hotel brochure vocabulary. High praise of the breakfast with the extensive list of everything available on the buffet. Occasional recommandation for the wonderful restaurant next door. Specific spelling or grammar mistake that keeps coming back. Tons of positive votes for the fake reviews, tons of negative votes for the real all-the-more-negative reviews, almost no votes for the real positive or neutral reviews.
Those hotels should be avoided like the plague, because it shows their only goal : trick people into booking them. That and being oblivious to the critique, being absolutely sure that nothing is wrong with their establishment.
On the brighter side, I like to read the George V reviews every now and then. I believe they are all perfectly real, but it's a lot of fun anyway.
"Telepathic service", "I went there for one night three years ago and the manager remembered my kids names", "the bell boy teached tricks to my dog", "the breakfast bus boy spoke fluent Japanese"... this place seems out of this world