We have evidence to the contrary. Two blog articles and two preprints of fake academic articles [0] were able to convince CoPilot, Gemini, ChatGPT and Perplexity AI of the existence of a fake disease, against all majority consensus. And even though the falsity of this information was made public by the author of the experiment and the results of their actions were widely published, it took a while before the models started to get wind of it and stopped treating the fake disease as real. Imagine what you can do if you publish false information and have absolutely no reason to later reveal that you did so in the first place.