You need to want to know what is true first, to care enough to take the trouble of knowing how to detect bullshit. I think the reason why bullshit is flourishing is because those that actually give a damn are the minority. The majority is composed of the useful idiots and those that manipulate them. Of course reality is never black and white, and it is much more nuanced than I've stated here, but I think that's the general gist of things
A big problem is that for most people, truth has no direct or measurable value in lives. Information is mostly used as social objects - something to talk about and share with other people. It doesn't matter whether e.g. that GMO-causes-cancer paper is solid or a hoax, what matters is that as the story circulates, you can play the relative status game with your friends by showing who's more into GMO-causes-cancer belief.
In the areas where "getting things right" has a direct impact on someone's life, people turn out to be surprisingly good at catering for their own interests (though not perfect, and the whole advertising industry is based around the desire to screw people in this area).