This is a way of abusing a human tendency of "getting to the point" (I believe there is a technical term for this but it slips my mind).
Fnords are almost exclusively applied in news articles, be it online or in newspapers. As you might imagine not many people read articles thoroughly.
They see a headline and just glaze over the sentences searching for the most "relevant parts". This is where the magic starts. Since the main interest of the reader
is to get the gist of what's being said in the article as soon as possible and get on with his life, fnords stick out as a sore thumb among the text. Your brain believes
it singled out these words willingly, to speed up the process. when in fact they were put there on purpose for you to notice.
Now, there is most certainly a method to this, and it's complexity depends on how effective you want it to be. The first step is identifying or even creating fnords
out of thin air. News corporations usually have teams that analyze and survey how people react to certain words and phrases. More specifically what emotions and ideas
are associated with them.
But of course, if you're sufficiently in touch with the culture(s) you're working with, using fnords will come quite naturally since you will be able to predict people's
reactions with sufficient accuracy by introspecting your own reactions.