Some years ago I made the mistake of selling French cars. They...

Some years ago I made the mistake of selling French cars. They broke down far more that they should. As a dealership and sales staff we were immersed in our world of failing cars and dint know that other people (certain Japanese makers, for example) made cars that just continued to work. One customer bought and had troubles. That customer worked at the same city council as one of our prospective customers and told that prospective customer about the issues with their French car. The prospective customer went onto a French car forum with the result that he would never buy a French car. Don't believe me? Go to Aussiefrogs and hear the wailing, whinging and nashing of teeth and you wont buy one either.
That was part of the reason I stopped selling those cars.
Yes, forums influence purchase decisions including stock purchases and therfore SP by extension.