Sure, but it increases friction that forces a re-eval of cost/benefit of the bot(s).
Newest captcha services are a prediction score, not even a verification screen, and you can feed polluting data to bots you are certain to exist.
Newest captcha services are a prediction score, not even a verification screen, and you can feed polluting data to bots you are certain to exist.
For OP, I think simply not returning results at all is a more practical measure because it removes the reward completely. Captchas and bot detection keep the reward in play, while taking away the results entirely makes the entire pursuit futile.
If anything, it might be best to return a page that explicitly states "Sorry, this search engine no longer supports SEO footprint search queries."
*edit for typo & wording