Yelp, BBB, anyone who has a way to get money from the reviewed companies/professionals... impossible to remain unbiased. Haven't trusted, will never trust. Have a hard time believing Angie's List doesn't have the same issue in the other direction.
Finding unbiased, un-"washed" reviews is NP-hard :/
Finding unbiased, un-"washed" reviews is NP-hard :/