There are lots of fake recipe books on amazon for instance. But how can you really be sure without trying the recipes? It might look like a recipe at first glance, but if its telling you to use the right ingredients in a subtly-wrong way, its hard to tell at first glance that you won't actually end up with edible food. Some examples are easy to point at, like the case of the recipe book that lists Zelda food items as ingredients, but they aren't always that obvious.
I saw someone giving programming advice on discord a few weeks ago. Advice that was blatantly copy/pasted from chat GPT in response to a very specific technical question. It looked like an answer at first glance, but the file type of the config file chat GPT provided wasn't correct, and on top of that it was just making up config options in attempt to solve the problem. I told the user this, they deleted their response and admitted it was from chatGPT. However, the user asking the question didn't know the intricacies of "what config options are available" and "what file types are valid configuration files". This could have wasted so much of their time, dealing with further errors about invalid config files, or options that did not exist.