I'm positing a model where a third party does the influencing, not the company delivering the LLM/service. What's to say that it's an ad if the Wikipedia page for a product itself says that the product "establishes new standards for quality, technological leadership and operating excellence". (and no problem if the edit gets reverted, as long as it said that just at the moment company X crawled Wikipedia for the latest training round).

So more like SEO firms "helping you" move your rank on Google, than Google selling ads.

I'd imagine "undetectable to the LLM training orgs" might just be service with a higher fee.