It will be: GPT output is usually either garbage, repetitive, very wrong, subtly wrong, or inconsistent in writing style in a way humans aren't. (It sort of starts trying to say something different, in the "same style" as it started with, then switches style later.)
When humans really can't tell the difference, well… https://xkcd.com/810/ seems appropriate.
At some point you also run up against the virus vs immune system endgame: it's evolutionarily inefficient to optimally outwit an adversarial system.
Usually there exists a local maximum where you obtain most of the value with less-than-full effort.
Sadly, the centralization of search directly cuts against that. I.e. outwitting Google search = $$$$ vs outwitting 1-or-4 equally-used search engines = $. :(
When humans really can't tell the difference, well… https://xkcd.com/810/ seems appropriate.