http://www.perlmonks.org?node_id=872000


in reply to Battling form spam

I find that almost no spam-bots are the slightest bit “clever.”   The malcontents that run them usually get a scoop of URLs, say from Google, and start slamming random data (“prescription drugs without a prescription, anyone?”) into them.   They really aren’t out to trash your website out of the hundreds or thousands of URLs that might be on their trash-list.

So... put almost anything on the site which may require any sort of specific human input.   (Put the instructions somewhere besides a “label” that is adjacent to the field in question.)   The bots will consistently fail that test, and the bot-owners (who are busy burning in hell...) will never actually bother to find out why.