Yikes, that is a visual! However, it does make a point!
The questions is, do you tell someone when they have food in their teeth, their pants are ripped, or their girlfriend is hanging with someone else? This is a quandary that many people wrestle with. If it's a friend, you might feel a certain moral responsibility, and possibly more comfortable sharing with them when something is askew. If it is a stranger, the lines may be a bit blurred.
However, what about when it isn't necessarily something of a personal nature, but you feel the business could benefit from your disclosure? It doesn't have to be a big deal. If your experience is less than optimal because a business is doing something wrong or not providing the kind of service they are capable of, then it might be your obligation to say something. It doesn't mean you have to be a habitual complainer, but a few words about how your experience has been negatively impacted might be greatly appreciated.
Everyone has to weigh for themselves as to whether they should disclose their dissatisfaction or if they notice something is wrong, but if you imagine sharing it with your best friend and come at it from a helpful and considerate attitude, both parties will benefit.