It only works at the low level and for the really brainless stuff.

There are a lot of things which beyond a certain level require domain specific expertise to spot the bullshit.

One of the first things the genuine skeptic figures out is the limits of one's own capability to evaluate information.

You can use some heuristics to try and spot greedy/marketing bollocks even in domains you don't understand in depth (for example: cui bono - if those pushing a message benefit from others believing it, it instantly goes into the "untrusted" mental bucket) but even that only goes so far (it's not by chance that, for example, in politics and economics most Think Tanks hide their sources of funding: it hides the direct link between "studies" they publish those who fund them benefiting if the public and politicians believe those "studies").

In summary, do it whilst being aware that we're all limited and as smart as one is there are plenty of equally smart people who make money from swindling others.