i do not know if protector well prevent all Bad Bots but i run on my Xoops such Cool Script to Catch the Bad Bots its called Spider Trap you can find it http://www.spider-trap.de/

you have just to install the script on your site then add Hidden link somwhere in your theme to link to index.php inside the Spider trap folder . when the bad bot ignore's robot.txt file the script will ban them and if Human clicked the link by Mistake they can unban thier self by write the captacha code they will get in the ban page . to understand it just try click the trap link here and u will get banned

http://www.spider-trap.de//spider-trap/index.php