Good old Hans Myers. I believe he called himself the Reverend. I think he may be the only member we ever banned for bad behavior.
AFAIK, he just took advantage of a couple of kind hosts by staying too long - he was in fact a sponger, not a bike tourist.
We probably don't have two complaints a year about members, and when we do it usually turns out to be that one party was inconsiderate.
I encourage you all to read the FAQ, which is available without logging in:
http://warmshowers.org/faq. It's very clear there that you're never under any obligation to host, and that guests are never to arrive at your place without prior arrangement. These are clearly spelled out in the "rules" at
http://warmshowers.org/the_rules.
-Randy Fay (webmaster of Warmshowers.org)