It does work, on two levels:

1. Simple, cheap, easy-to-detect bots will scrape the poison, and feed links to expensive-to-run browser-based bots that you can't detect in any other way.

2. Once you see a browser visit a bullshit link, you insta-ban it, as you can now see that it is a bot because it has been poisoned with the bullshit data.

My personal preference is using iocaine for this purpose though, in order to protect the entire server as opposed to a single site.