One point is made regarding class reviews (often called "After Action Reports" online, as though a pistol class were some kind of real-life shootout) from other students:
There is, however, a catch: Whenever you are reading an AAR, be aware that trainers and companies understand the potential marketing value of AAR’s, so don’t necessarily take the AAR at face value. Beware the guy who seems to have trained primarily with one particular trainer or school, as he might be more of a groupie than a customer. The most useful reviews are generally produced by individuals who have a significant training background with a number of different instructors, especially armed professionals who have been at it a while.Beware the man with one trainer, as he has probably been successfully marketed to.
Just like the conventional punchy-kicky martial arts, there is a tremendous amount of fanboyism and testosterone-by-association in the shooty martial arts. ("Sensei Kliklikbang is an absolute badass, and because I took classes from him, so am I. Wouldn't you like to be a badass, too?")
Additionally, some instructors have rabid cult followings, and many seem to actively encourage this, since it is, at the end of the day, a business, and loyal fanboys are not only repeat customers but also evangelical word-of-mouth advertisements.
Just because an instructor has, or even encourages, groupies doesn't mean they're necessarily a bad instructor, but it's important to take the breadth of someone's training resume into account when reading yet another "my sensei can beat your sensei up" review on the internet.
One immediate turn-off to me is an instructor who has the One True System©®™ and actively discourages pupils from seeking training with other schools or constantly trash-talks other instructors. That's a big ol' red flag in my eyes: It tells me that his business model or his cult of personality is more important to him than is seeing his students become better shooters.