Most crawlers don't care - they're purely downloading. Most garbage will also be filtered out before training, and generating plausible garbage is expensive - not really worth the trouble. What you can do with the garbage, is that you can place unique identifiers in the links you serve, so when a crawler that you can't recognize otherwise comes visiting a poisoned URL, you can firewall it off. This works because the crawlers use a queue: they get a list of URLs to visit, they download them, and later on, the URLs from those get extracted, and crawlers will visit those URLs.

So if you manage to trap a bot, and overwhelm its queue with poisoned URLs, you can also catch bots that you wouldn't be able to easily identify otherwise. And that is why serving an endless maze of garbage is so very useful. Because it lets you catch stuff like headless chromes operating through residential proxies: because those too, follow a queue.

As some other users have already mentioned it, have a look at this project anyway: https://iocaine.madhouse-project.org/

It gives much more bloated information for a crawler than I expected. But sounds quite fun to host.