HerrGrau
(you can also note if all of the reviews are written over a short period of time). I saw one company having teachers fill out google reviews.
One note, that a grouping of reviews does not indicate anything suspicious actually. For example, we often do pushes for BSchool reviews at regular intervals (e.g. fall, spring, summer) and we will often get 20-40 reviews submitted within a few days. We then review and publish all of them usually on the same day, so it may look suddenly suspicious that we have 3 Reviews for Kellogg on the same day after not getting any for 3 months. That's not because i got super prolific and decided to post some fakers (i really have better things to do and what a miserable job that would be) but it is because we sent out an email to all of the current students.... which we probably should do about now.
In terms of reviews, Google, Yelp, and anything that does not require customer verification is going to be too tempting for "unknown" and "young" companies to trick the system. For example, once you reach a certain level at Yelp, they consider everything you post to be genuine. As the result, companies have been posting ads on craigslist looking for "Yelp gurus" and consultants to help promote certain products and businesses. It is possible to buy reviews on Yelp and google is even easier - you can just get a gmail account. On GMAT Club, we require many more hoops to jump and have additional levels of verification including IP address checking and other things I don't really want to disclose fully for obvious reasons. While I am not saying it is absolutely impossible to game the system (nothing is absolute), it is impossible to game it on a scale that would be practical or meaningful.
As to the whole industry and prep services, you really have to look at multiple elements and it goes beyond numbers, kind of just like profiles of people applying to BSchools. GMAT score tells only a part of the story.
1. A lot of courses these days are not involving an instructor. It is all online/recorded/perfected content that has been optimized and frankly, may be much better than you would have gotten from a live instructor may have been tired one of the classes, was sick during another, and so on.
2. Some companies have myriads of tutors but they contract out. I know a few companies that tutor a variety of subjects for High School, College, and also GMAT applicants. Anyone can tutor for them and anyone can apply - they provide a short description of how they work and how you should work with customers but it is nothing like the extensive training
MGMAT requires for example. They take the "social" and "sharing economy" concept where anyone with a Prius can be a cab driver and now anyone with a high GMAT score can be a tutor.
3. As to instructors having to score a certain score - that's a good rule. I am not sure however, that scoring just a certain percentile is sufficient enough, however. Here is an example of a guy who claims to have studied for 2 days and scored 770 -
https://gmatclub.com/forum/640-to-770-b ... 39439.html. I have seen a few of these over the years... some probably fakes but some are true, and while these guys would pass the "percentile test" with flying colors, I don't think they would make good teachers.
4. I believe, an ideal Tutor also needs to show a certain level of improvement since most of their customers would be an audience of people who have scored 550 or even less than that. Otherwise, you don't speak the same language or facing the same issues. It is kind of like a billionaire giving tips about money to the poor - many pay attention to them but when you listen in, you get a lecture about tax shelters, minimizing taxes on transaction costs, and tips for buying private jets. Not helpful when you make $10/hr. The same is here, it is not good enough just to score - you need to have been in the shoes of despair, you need to have been "GMAT-poor" and dug yourself out of the hole. Otherwise, you could easily have been a genius who easily scored 760 without putting any work into it and keeps saying it is "easy."
There is no perfect measure besides reputation and feedback... and that's for a course instructor. If you are looking for a tutor, there are many more things that come into play - personality, learning styles, mutual respect, judgement-free environment, etc, etc.