Here are 5 important things to understand about the review filter:
1. Reviews that reflect perfectly legitimate experiences are sometimes filtered out by the review filter's algorithmic processes. We agree this can be frustrating, but it's the high cost we accept to avoid being a lassez-faire review site that people stop using. Everyone loses when that happens.
2. Reviews are never "deleted" by the review filter; they are always shown on users' profile pages. The review filter simply syndicates established users' reviews from their user pages onto business pages. This automated process sometimes creates the perception that reviews are being deleted and re-added over time; what's actually happening is users are becoming more-or-less established over time.
3. The best word of mouth is organic and unsolicited. As counter-intuitive as it may seem, Yelp discourages business owners from asking people to write reviews about their businesses. It's tough for an algorithm to tell the difference between a business owner aggressively putting a laptop in front of a client and saying, "Give me 5 stars!" and that same business owner flipping the laptop around and manufacturing a fake 5-star review about themselves.
4. We're purposely not elaborate about all the variables that go into defining an "established" user, because it's a Catch-22: the more descriptive we are about what makes an established user, the less effective our filter is at fighting shills and malicious content.
5. Both positive and negative reviews can be affected. This is to protect Car Mechanic A from Car Mechanic B's writing of malicious 1-star reviews about his competitor. It also protects someone with a toothache from being lured into the wrong dentist's office based on 25 fake 5-star reviews he wrote himself.