Typically display none will do but you can also have white on white text with no tabindex or off screen absolute positioning, etc.
I say this as someone who has had to combat this specific technique - I'd suggest that if you believe it works, it's probably because you saw obvious scraping activity stop when you did it, but you were never aware of the more professional scraping that adapted to it or was never caught by it in the first place.
Whenever I've scraped a website, I am extremely careful not to request more pages than I need. A better method for blocking them is to flag requests for resources that do not proceed in a logical manner. For example, if you have an API endpoint that displays the information scrapers want, that endpoint should have a specific "route" through the user interface. If you find requests directly to that resource without first proceeding through the typical UI flow, that is more accurate for identifying a scraper.
This is still not foolproof, because the scraper can just script requests to the requires series of pages in order. But it's a good start for getting rid of most scrapers. The most effective method for getting rid of scrapers is IP agnostic behavior analysis, because it can catch e.g. scrapers trying to parallelize requests that increment across a proxy farm or requests that don't obey typical behavior constraints in the UI.
Wouldn't block specialised scrapers as they would know to avoid that URL/link (though they'd probably work it out anyway), but would still limit more broad crawlers.
I have found that advanced bot mitigation is the single most significant determining factor of PPC ROI, which is a sad commentary on the current state of the paid advertising ecosystem.
To answer your question, based on my personal experience, I'd say on average, for display campaigns (specifically not referring to Google search ads, which tend to have a lower percentage of bot traffic - while Bing is the Wild Wild West)...I'd say overall it's somewhere in the 30% neighborhood. Not all of those have malicious intent, but in PPC, every non-human click on your ads is malicious.
Regardless of niche, realtime bot mitigation is probably the best competitive advantage that one can have in the PPC arena.