Looking at the actual filtered reviews for the restaurant mentioned, it's pretty easy to make some guesses about the "secret" algorithm. Very good or very bad reviews by people who have little history with the site, few reviews, minimal social involvement, or possibly a number of user-flagged previous reviews, get filtered. Being short and perfunctory appears to be a ding, too. A positive, filtered review: "New Year's Eve dinner 2011 was Great!! We have been coming here since 2005 and have never had anthing but a good time and great food . We live in San Jose and this is where we prefer to come for Italian. Mike and Lalo are always so nice and friendly, they make us feel at home. Mr. Bob isn't so bad either. Tiramisu Martini's really? Its a must and it was quite tasty. Hope 2012 is a Great Year for all." No profile picture, zero friends, and it's the user's only Yelp. A negative, filtered review: "The worst attitude towards their guests I have ever seen. The waiter refused to make any accommodations to their menu with a curt, "No," and the manager refused to accept a voucher from the restaurant because it was a "Special Evening" and said he would call the police rather than honor it!!! An expensive, average meal was bad enough but to be abused on top of it was really too much. Oh, but the bread was excellent. You can get it (or better) down the street at Boudin, take my advice and go there." A profile pic is displayed, but the user has no friends and no other reviews. There are also 8 four or five star reviews removed completely for violations of Yelp's guidelines -- presumably, the restaurateur or his friends were believed to have posted them, rather than "real" diners.