Of course shared passwords often DO indicate cracking - they crack your
site to get the passwords, then post them everywhere. There are some
ways to prevent both the cracking and the sharing. The link below has
some tips on how to first find out if your password file has been cracked,
then how to find out HOW t was cracked, and how to PREVENT that from
happening at all or happening again. The bottom half of the page is most
useful if the whole password file hasn't been cracked yet - it tells you how
to prevent that, mostly without spending any money
http://bettercgi.com/strongbox/passg...adyhacked.html
To detect and prevent password sharing, Strongbox is of course pretty
much the industry standard nowadays, kind of like CCBill is the most
recommended processor:
https://www.bettercgi.com/strongbox/