The warning reads: "TripAdvisor has reasonable cause to believe that either this property or individuals associated with the property may have attempted to manipulate our popularity index by interfering with the unbiased nature of our reviews. Please take this into consideration when researching your travel plans."
This doesn't come as a surprise to most, as it's a good opportunity to promote your properties. Beat of Hawaii, an Expedia owned company, and Arthur Frommer have been complaining about TripAdvisor for a long time, for failing to police against fake reviews.
It's always a good idea to double check any property with a few different websites, or with your Travel Agent, to make sure you're making a good choice.