Of course not -- I don't claim any sort of omniscience, although I do see where you're going with this.
People who are aware of Company A's polluting habits will gladly patronize Company B instead -- unaware that Company B is at least as big a polluter.
Contrawise, people who know about Company B will shop at Company A -- because they only have the other half of the story.
Meanwhile, Company C does more damage to the environment than Companies A and B put together, but they've managed to keep it out of the press (since the EPA only has about 50 people checking for dumpers anyway, and Company C has paid off the people who hire those 50), and they've lowered their prices to attract the people who couldn't afford the other two anyway.
Now, if consumers got organized and worked together, they could definitely affect the market (and more importantly, the environment) in positive ways -- which puts it in the best interests of the companies (and the politicians they've bought and paid for), to keep the consumers at each others' throats, preferably with a slew of manufactured non-issues, to prevent them from ever wanting to listen to -- let alone work with -- people who aren't their ideological twins.
Divide et impera.