My worst offender for scraping one of my sites was Anthropic. I deployed an ai tar pit (https://news.ycombinator.com/item?id=42725147) to see what it would do it with it, and Anthropic's crawler kept scraping it for weeks. I calculated the logs and I think I wasted nearly a year of their time in total, because they were crawling in parallel. Other scrapers weren't so persistent.