Haha, just kidding, I'm not going to tell the botrunners everything I know. Though admittedly your average robot is too stupid to live, so it wouldn't matter how much information you handed them on a plate.
I've just wrapped up a project that started about a month and a half ago.
Old htaccess shared by 6 sites:
29.4k
500-odd lines, including
57 lines of bad user-agents
14 lines of bad referers
New shared htaccess:
4.5k
150 lines, including
16 lines of bad user-agents
1 (one) bad referer
Time will tell, but a quick look at access logs from shortly after The Great Change reveals at least one unwanted visitor 403'd, and at least one law-abiding robot admitted.
Tralala.