Why does this work?
Basically under capitalism, the worst thing you can possibly do to a product or service (and books, movies, video games etc. are products first and foremost under capitalism) is to not buy it. And that is the default position. If you are unaware a product or service even exists, how could you possibly buy it? So if there is a scandal involving the product or its creator, the mere fact that it makes more people aware of its existence - even if all but one of those made thus aware are now firmly convinced to never, ever buy that thing - it still results in a net increase of people buying this thing. The same is true by analogy for a political party or candidate in a system where you cannot explicitly vote against something (as in, not "vote the other party/gal/guy" but "vote for not x" or give x negative votes), it is often advisable for a long shot or outsider candidate to say or do outrageous things to be covered by the media (even if only for "look at that fool") because even the vast majority of the electorate hating you is better than the default reaction of "who?" which results in zero votes. Also, if you are being entertaining while being outrageous, this will cause at the very least a Vocal Minority to root for you, support you and become your base - For the Lulz. Any similarity with real politicians living or dead is of course entirely coincidental.
Now, what can be done against this? Frankly, for products little besides explicit regulation (e.g. "You can't say or imply in your ads that the competition murders baby puppies"), because the only thing that would work is a pact for everyone to not buy a product whose ad campaigns are built on shock value. And "everyone" cannot even agree the Earth is mostly spherical. In political systems built on coalition building, it might help to explicitly exclude the "out there" party from any serious coalition talks and even do a Rivals Team Up to keep them from power if that's the only other option - still, that can of course also backfire. In general, the worst thing that can happen to someone who deliberately tries to invoke this trope is being utterly ignored.
