Great, so you've updated your knowledge base, it's got garbage targeted to make it attractive to the model, and now your model is outputting garbage. It's the exact same problem Google has fighting the SEO spammers. Now the model is significantly less useful, exactly as suggested.
We've already seen exactly this happened with search. There's no reason to believe that LLMs are immune.
We've already seen exactly this happened with search. There's no reason to believe that LLMs are immune.