Here's the high level description of how it works.

• Create a directory like /honeypot/ on your site
• Put some code in index.php within the directory
• Add the honeypot as an explicit "Disallow" in robots.txt
• Include a hidden link to to the honeypot on every page of your site
• If something accesses that page, write its IP address to your .htaccess
• The .htaccess bans the IP address from ever accessing your site again.

But, I thought that scrapers often used proxy networks so they retrieve through huge amounts of IP's.